GHSA-P423-J2CM-9VMQ

Vulnerability from github – Published: 2026-04-08 19:23 – Updated: 2026-06-05 17:52
VLAI
Summary
Cryptography vulnerable to buffer overflow if non-contiguous buffers were passed to APIs
Details

If a non-contiguous buffer was passed to APIs which accepted Python buffers (e.g. Hash.update()), this could lead to buffer overflows. For example:

h = Hash(SHA256())
b.update(buf[::-1])

would read past the end of the buffer on Python >3.11

Severity
6.9 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "cryptography"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "45.0.0"
            },
            {
              "fixed": "46.0.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-39892"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-119"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-08T19:23:08Z",
    "nvd_published_at": "2026-04-08T21:17:01Z",
    "severity": "MODERATE"
  },
  "details": "If a non-contiguous buffer was passed to APIs which accepted Python buffers (e.g. `Hash.update()`), this could lead to buffer overflows. For example:\n\n```python\nh = Hash(SHA256())\nb.update(buf[::-1])\n```\n\nwould read past the end of the buffer on Python \u003e3.11",
  "id": "GHSA-p423-j2cm-9vmq",
  "modified": "2026-06-05T17:52:21Z",
  "published": "2026-04-08T19:23:08Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/pyca/cryptography/security/advisories/GHSA-p423-j2cm-9vmq"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-39892"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/pyca/cryptography"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/cryptography/PYSEC-2026-36.yaml"
    },
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2026/04/08/12"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Cryptography vulnerable to buffer overflow if non-contiguous buffers were passed to APIs"
}


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