GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

BREW-CHECKOV-CVE-2026-34520 (GHSA-63HF-3VF5-4WQF)

Vulnerability from osv_homebrew – Published: 2026-08-13 16:39 – Updated: 2026-09-17 19:53 – Source website
VLAI
Summary
AIOHTTP's C parser (llhttp) accepts null bytes and control characters in response header values - header injection/security bypass
Details

Summary

The C parser (the default for most installs) accepted null bytes and control characters in request headers.

Impact

An attacker could send header values that are interpreted differently than expected due to the presence of control characters. For example, request.url.origin() may return a different value than the raw Host header, or what a reverse proxy interpreted it as., potentially resulting in some kind of security bypass.

Patch: https://github.com/aio-libs/aiohttp/commit/9370b9714a7a56003cacd31a9b4ae16eab109ba4

Severity
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
2.7 (Low)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "fix": "bump",
        "range_state": "fixed",
        "resource": "aiohttp",
        "resource_purl": "pkg:pypi/aiohttp@3.14.3",
        "upstream_fixed_in": "3.13.4"
      },
      "package": {
        "ecosystem": "Homebrew",
        "name": "checkov",
        "purl": "pkg:brew/checkov"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.0.615"
            },
            {
              "fixed": "3.2.510_2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "confidence": "high",
    "source": "matched",
    "strategy": "registry",
    "upstream_evidence": [
      {
        "ecosystem": "PyPI",
        "key": "pkg:pypi/aiohttp@3.14.3",
        "name": "aiohttp",
        "resource": "aiohttp",
        "strategy": "registry",
        "subject_version": "3.14.3"
      }
    ]
  },
  "details": "### Summary\n\nThe C parser (the default for most installs) accepted null bytes and control characters in request headers.\n\n### Impact\n\nAn attacker could send header values that are interpreted differently than expected due to the presence of control characters. For example, `request.url.origin()` may return a different value than the raw Host header, or what a reverse proxy interpreted it as., potentially resulting in some kind of security bypass.\n\n-----\n\nPatch: https://github.com/aio-libs/aiohttp/commit/9370b9714a7a56003cacd31a9b4ae16eab109ba4",
  "id": "BREW-checkov-CVE-2026-34520",
  "modified": "2026-09-17T19:53:35Z",
  "published": "2026-08-13T16:39:32Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/aio-libs/aiohttp/security/advisories/GHSA-63hf-3vf5-4wqf"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-34520"
    },
    {
      "type": "WEB",
      "url": "https://github.com/aio-libs/aiohttp/commit/9370b9714a7a56003cacd31a9b4ae16eab109ba4"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/aio-libs/aiohttp"
    },
    {
      "type": "WEB",
      "url": "https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/aiohttp/PYSEC-2026-2102.yaml"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U",
      "type": "CVSS_V4"
    }
  ],
  "summary": "AIOHTTP\u0027s C parser (llhttp) accepts null bytes and control characters in response header values - header injection/security bypass",
  "upstream": [
    "GHSA-63hf-3vf5-4wqf",
    "CVE-2026-34520",
    "PYSEC-2026-2102"
  ]
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.