hpack: golang.org/x/net/http2/hpack: hpack: Denial of Service via malformed HTTP/2 header encoding

cve CVE-2026-59980 3 sources, 4 claims · Watch

Red Hat writes:
hpack: golang.org/x/net/http2/hpack: hpack: Denial of Service via malformed HTTP/2 header encoding the claim

What it is to other things

In words only, so not counted until a person confirms one:

affectspython_hyper/hpack
NVD says “python-hyper · hpack”
made_bypython_hyper
NVD says “python-hyper”

What each source says

PropertySourceSaidMeans here
Cvss
cvss
Red Hat5.3
receipt
Source
Red Hat
Its words
5.3
Read by
field:cvss3_score
Said since
2026-09-29 09:44 UTC
Last answered
2026-10-04 00:12 UTC
Original
open at the source
What the source handed over
{
  "CVE": "CVE-2026-59980",
  "CWE": "CWE-770",
  "advisories": [],
  "affected_packages": [],
  "bugzilla": "2539827",
  "bugzilla_description": "hpack: golang.org/x/net/http2/hpack: hpack: Denial of Service via malformed HTTP/2 header encoding",
  "cvss3_score": "5.3",
  "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
  "cvss_score": null,
  "cvss_scoring_vector": null,
  "package_state": null,
  "public_date": "2026-09-23T22:07:35Z",
  "resource_url": "https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-59980.json",
  "severity": "low"
}
—
Cwe
cwe
not compared		GitHub advisoriesCWE-400
receipt
Source
GitHub advisories
Said since
2026-09-26 15:00 UTC
Last answered
2026-10-04 00:10 UTC
Original
open at the source

This source has not kept a receipt for this claim yet. The next update that reads it will.

—
Cwe
cwe
not compared		Red HatCWE-770
receipt
Source
Red Hat
Its words
CWE-770
Read by
field:CWE
Said since
2026-09-29 09:44 UTC
Last answered
2026-10-04 00:12 UTC
Original
open at the source
What the source handed over
{
  "CVE": "CVE-2026-59980",
  "CWE": "CWE-770",
  "advisories": [],
  "affected_packages": [],
  "bugzilla": "2539827",
  "bugzilla_description": "hpack: golang.org/x/net/http2/hpack: hpack: Denial of Service via malformed HTTP/2 header encoding",
  "cvss3_score": "5.3",
  "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
  "cvss_score": null,
  "cvss_scoring_vector": null,
  "package_state": null,
  "public_date": "2026-09-23T22:07:35Z",
  "resource_url": "https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-59980.json",
  "severity": "low"
}
—
Ecosystem
ecosystem
GitHub advisoriespip
receipt
Source
GitHub advisories
Said since
2026-09-26 15:00 UTC
Last answered
2026-10-04 00:10 UTC
Original
open at the source

This source has not kept a receipt for this claim yet. The next update that reads it will.

—
Product
product
NVDhpack
receipt
Source
NVD
Its words
hpack
Read by
field:cve.affected[].affectedData[].product
Said since
2026-09-29 17:49 UTC
Last answered
2026-10-04 00:12 UTC
Original
open at the source
2026-09-29 17:49 UTChpack
2026-09-29 09:45 UTC—
What the source handed over
{
  "cve": {
    "affected": [
      {
        "affectedData": [
          {
            "product": "hpack",
            "vendor": "python-hyper",
            "versions": [
              {
                "status": "affected",
                "version": "< 4.2.0"
              }
            ]
          }
        ],
        "source": "security-advisories@github.com"
      }
    ],
    "cveTags": [],
    "descriptions": [
      {
        "lang": "en",
        "value": "hpack is an HTTP/2 Header Encoding for Python. Prior to version 4.2.0, unbounded variable integer decoding can cause run-away computation on malformed input leading to O(n^2) runtime, effectively blocking further processing with large enough unsanitized input. A fix is available in python-hyper/hpack v4.2.0 to restricted variable integer decoding to uint32 to prevent run-away computation. As a workaround, sanitize input to hpack decoder for long sequences of `0xFF` values to prevent malicious use."
      }
    ],
    "id": "CVE-2026-59980",
    "lastModified": "2026-09-30T17:32:07.107",
    "metrics": {
      "cvssMetricV40": [
        {
          "cvssData": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "availabilityRequirement": "NOT_DEFINED",
            "baseScore": 6.3,
            "baseSeverity": "MEDIUM",
            "confidentialityRequirement": "NOT_DEFINED",
            "exploitMaturity": "NOT_DEFINED",
            "integrityRequirement": "NOT_DEFINED",
            "modifiedAttackComplexity": "NOT_DEFINED",
            "modifiedAttackRequirements": "NOT_DEFINED",
            "modifiedAttackVector": "NOT_DEFINED",
            "modifiedPrivilegesRequired": "NOT_DEFINED",
            "modifiedSubAvailabilityImpact": "NOT_DEFINED",
            "modifiedSubConfidentialityImpact": "NOT_DEFINED",
            "modifiedSubIntegrityImpact": "NOT_DEFINED",
            "modifiedUserInteraction": "NOT_DEFINED",
            "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
            "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
            "modifiedVulnIntegrityImpact": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
            "version": "4.0",
            "vulnAvailabilityImpact": "LOW",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "source": "security-advisories@github.com",
          "type": "Secondary"
        }
      ],
      "ssvcV203": [
        {
          "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "ssvcData": {
            "id": "CVE-2026-59980",
            "options": [
              {
                "exploitation": "none"
              },
              {
                "automatable": "no"
              },
              {
                "technicalImpact": "partial"
              }
            ],
            "role": "CISA Coordinator",
            "timestamp": "2026-09-24T13:24:31.887152Z",
            "version": "2.0.3"
          }
        }
      ]
    },
    "published": "2026-09-23T23:17:11.473",
    "references": [
      {
        "source": "security-advisories@github.com",
        "url": "https://cs.opensource.google/go/x/net/+/master:http2/hpack/hpack.go;l=468;drc=8e2b117aee74f6b86c207a808b0255de45c0a18a"
      },
      {
        "source": "security-advisories@github.com",
        "url": "https://docs.rs/http2/0.5.19/src/http2/hpack/decoder.rs.html#403"
      },
      {
        "source": "security-advisories@github.com",
        "url": "https://github.com/python-hyper/hpack/commit/8cfb02c547740e16dbfe7aba77bad84b297cec2c"
      },
      {
        "source": "security-advisories@github.com",
        "url": "https://github.com/python-hyper/hpack/security/advisories/GHSA-8v8h-hg4w-mvq2"
      }
    ],
    "sourceIdentifier": "security-advisories@github.com",
    "vulnStatus": "Deferred",
    "weaknesses": [
      {
        "description": [
          {
            "lang": "en",
            "value": "CWE-400"
          }
        ],
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  }
}
—
Severity
severity
conflict		GitHub advisoriesmedium
receipt
Source
GitHub advisories
Said since
2026-09-26 15:00 UTC
Last answered
2026-10-04 00:10 UTC
Original
open at the source

This source has not kept a receipt for this claim yet. The next update that reads it will.

—
Severity
severity
conflict		Red Hatlow
A flaw that is unlikely to be exploited, or whose impact is minimal.
receipt
Source
Red Hat
Its words
low
Read by
field:severity
Said since
2026-09-29 09:44 UTC
Last answered
2026-10-04 00:12 UTC
Original
open at the source
What the source handed over
{
  "CVE": "CVE-2026-59980",
  "CWE": "CWE-770",
  "advisories": [],
  "affected_packages": [],
  "bugzilla": "2539827",
  "bugzilla_description": "hpack: golang.org/x/net/http2/hpack: hpack: Denial of Service via malformed HTTP/2 header encoding",
  "cvss3_score": "5.3",
  "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
  "cvss_score": null,
  "cvss_scoring_vector": null,
  "package_state": null,
  "public_date": "2026-09-23T22:07:35Z",
  "resource_url": "https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-59980.json",
  "severity": "low"
}
—
Status
status
NVDDeferred
receipt
Source
NVD
Its words
Deferred
Read by
field:cve.vulnStatus
Said since
2026-10-02 12:00 UTC
Last answered
2026-10-04 00:12 UTC
Original
open at the source
2026-10-02 12:00 UTCDeferred
2026-09-29 09:45 UTCReceived
What the source handed over
{
  "cve": {
    "affected": [
      {
        "affectedData": [
          {
            "product": "hpack",
            "vendor": "python-hyper",
            "versions": [
              {
                "status": "affected",
                "version": "< 4.2.0"
              }
            ]
          }
        ],
        "source": "security-advisories@github.com"
      }
    ],
    "cveTags": [],
    "descriptions": [
      {
        "lang": "en",
        "value": "hpack is an HTTP/2 Header Encoding for Python. Prior to version 4.2.0, unbounded variable integer decoding can cause run-away computation on malformed input leading to O(n^2) runtime, effectively blocking further processing with large enough unsanitized input. A fix is available in python-hyper/hpack v4.2.0 to restricted variable integer decoding to uint32 to prevent run-away computation. As a workaround, sanitize input to hpack decoder for long sequences of `0xFF` values to prevent malicious use."
      }
    ],
    "id": "CVE-2026-59980",
    "lastModified": "2026-09-30T17:32:07.107",
    "metrics": {
      "cvssMetricV40": [
        {
          "cvssData": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "availabilityRequirement": "NOT_DEFINED",
            "baseScore": 6.3,
            "baseSeverity": "MEDIUM",
            "confidentialityRequirement": "NOT_DEFINED",
            "exploitMaturity": "NOT_DEFINED",
            "integrityRequirement": "NOT_DEFINED",
            "modifiedAttackComplexity": "NOT_DEFINED",
            "modifiedAttackRequirements": "NOT_DEFINED",
            "modifiedAttackVector": "NOT_DEFINED",
            "modifiedPrivilegesRequired": "NOT_DEFINED",
            "modifiedSubAvailabilityImpact": "NOT_DEFINED",
            "modifiedSubConfidentialityImpact": "NOT_DEFINED",
            "modifiedSubIntegrityImpact": "NOT_DEFINED",
            "modifiedUserInteraction": "NOT_DEFINED",
            "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
            "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
            "modifiedVulnIntegrityImpact": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
            "version": "4.0",
            "vulnAvailabilityImpact": "LOW",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "source": "security-advisories@github.com",
          "type": "Secondary"
        }
      ],
      "ssvcV203": [
        {
          "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "ssvcData": {
            "id": "CVE-2026-59980",
            "options": [
              {
                "exploitation": "none"
              },
              {
                "automatable": "no"
              },
              {
                "technicalImpact": "partial"
              }
            ],
            "role": "CISA Coordinator",
            "timestamp": "2026-09-24T13:24:31.887152Z",
            "version": "2.0.3"
          }
        }
      ]
    },
    "published": "2026-09-23T23:17:11.473",
    "references": [
      {
        "source": "security-advisories@github.com",
        "url": "https://cs.opensource.google/go/x/net/+/master:http2/hpack/hpack.go;l=468;drc=8e2b117aee74f6b86c207a808b0255de45c0a18a"
      },
      {
        "source": "security-advisories@github.com",
        "url": "https://docs.rs/http2/0.5.19/src/http2/hpack/decoder.rs.html#403"
      },
      {
        "source": "security-advisories@github.com",
        "url": "https://github.com/python-hyper/hpack/commit/8cfb02c547740e16dbfe7aba77bad84b297cec2c"
      },
      {
        "source": "security-advisories@github.com",
        "url": "https://github.com/python-hyper/hpack/security/advisories/GHSA-8v8h-hg4w-mvq2"
      }
    ],
    "sourceIdentifier": "security-advisories@github.com",
    "vulnStatus": "Deferred",
    "weaknesses": [
      {
        "description": [
          {
            "lang": "en",
            "value": "CWE-400"
          }
        ],
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  }
}
—
Vendor
vendor
NVDpython-hyper
receipt
Source
NVD
Its words
python-hyper
Read by
field:cve.affected[].affectedData[].vendor
Said since
2026-09-29 17:49 UTC
Last answered
2026-10-04 00:12 UTC
Original
open at the source
2026-09-29 17:49 UTCpython-hyper
2026-09-29 09:45 UTC—
What the source handed over
{
  "cve": {
    "affected": [
      {
        "affectedData": [
          {
            "product": "hpack",
            "vendor": "python-hyper",
            "versions": [
              {
                "status": "affected",
                "version": "< 4.2.0"
              }
            ]
          }
        ],
        "source": "security-advisories@github.com"
      }
    ],
    "cveTags": [],
    "descriptions": [
      {
        "lang": "en",
        "value": "hpack is an HTTP/2 Header Encoding for Python. Prior to version 4.2.0, unbounded variable integer decoding can cause run-away computation on malformed input leading to O(n^2) runtime, effectively blocking further processing with large enough unsanitized input. A fix is available in python-hyper/hpack v4.2.0 to restricted variable integer decoding to uint32 to prevent run-away computation. As a workaround, sanitize input to hpack decoder for long sequences of `0xFF` values to prevent malicious use."
      }
    ],
    "id": "CVE-2026-59980",
    "lastModified": "2026-09-30T17:32:07.107",
    "metrics": {
      "cvssMetricV40": [
        {
          "cvssData": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "availabilityRequirement": "NOT_DEFINED",
            "baseScore": 6.3,
            "baseSeverity": "MEDIUM",
            "confidentialityRequirement": "NOT_DEFINED",
            "exploitMaturity": "NOT_DEFINED",
            "integrityRequirement": "NOT_DEFINED",
            "modifiedAttackComplexity": "NOT_DEFINED",
            "modifiedAttackRequirements": "NOT_DEFINED",
            "modifiedAttackVector": "NOT_DEFINED",
            "modifiedPrivilegesRequired": "NOT_DEFINED",
            "modifiedSubAvailabilityImpact": "NOT_DEFINED",
            "modifiedSubConfidentialityImpact": "NOT_DEFINED",
            "modifiedSubIntegrityImpact": "NOT_DEFINED",
            "modifiedUserInteraction": "NOT_DEFINED",
            "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
            "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
            "modifiedVulnIntegrityImpact": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
            "version": "4.0",
            "vulnAvailabilityImpact": "LOW",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "source": "security-advisories@github.com",
          "type": "Secondary"
        }
      ],
      "ssvcV203": [
        {
          "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "ssvcData": {
            "id": "CVE-2026-59980",
            "options": [
              {
                "exploitation": "none"
              },
              {
                "automatable": "no"
              },
              {
                "technicalImpact": "partial"
              }
            ],
            "role": "CISA Coordinator",
            "timestamp": "2026-09-24T13:24:31.887152Z",
            "version": "2.0.3"
          }
        }
      ]
    },
    "published": "2026-09-23T23:17:11.473",
    "references": [
      {
        "source": "security-advisories@github.com",
        "url": "https://cs.opensource.google/go/x/net/+/master:http2/hpack/hpack.go;l=468;drc=8e2b117aee74f6b86c207a808b0255de45c0a18a"
      },
      {
        "source": "security-advisories@github.com",
        "url": "https://docs.rs/http2/0.5.19/src/http2/hpack/decoder.rs.html#403"
      },
      {
        "source": "security-advisories@github.com",
        "url": "https://github.com/python-hyper/hpack/commit/8cfb02c547740e16dbfe7aba77bad84b297cec2c"
      },
      {
        "source": "security-advisories@github.com",
        "url": "https://github.com/python-hyper/hpack/security/advisories/GHSA-8v8h-hg4w-mvq2"
      }
    ],
    "sourceIdentifier": "security-advisories@github.com",
    "vulnStatus": "Deferred",
    "weaknesses": [
      {
        "description": [
          {
            "lang": "en",
            "value": "CWE-400"
          }
        ],
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  }
}
—

vulnerability

hpack: golang.org/x/net/http2/hpack: hpack: Denial of Service via malformed HTTP/2 header encoding
zetlyn/cve-redhat · 2026-09-23
cvss 5.3 cwe CWE-770 severity low source
hpack is an HTTP/2 Header Encoding for Python. Prior to version 4.2.0, unbounded variable integer decoding can cause run-away computation on malformed input leading to O(n^2) runtime, effectively blocking further processing with large enough unsanitized input. A fix is available in python-hyper/hpack v4.2.0 to restricted variable integer decoding to uint32 to prevent run-away computation. As a workaround, sanitize input to hpack decoder for long sequences of `0xFF` values to prevent malicious use.
zetlyn/cve-nvd · 2026-09-23
product hpack status Deferred vendor python-hyper source
hpack: Unbounded variable integer decoding can cause run-away computation on malformed input
zetlyn/cve-ghsa · 2026-09-24
cwe CWE-400 ecosystem pip severity medium source
hpack: Unbounded variable integer decoding can cause run-away computation on malformed input
zetlyn/cve-ghsa · 2026-09-24
cwe CWE-400 ecosystem pip severity medium source