GHSA-w7pp-m8wf-vj6r
Vulnerability from github
Published
2023-02-07 20:54
Modified
2024-09-13 20:07
Severity ?
6.5 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
6.9 (Medium) - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
Summary
Cipher.update_into can corrupt memory if passed an immutable python object as the outbuf
Details

Previously, Cipher.update_into would accept Python objects which implement the buffer protocol, but provide only immutable buffers:

```pycon

outbuf = b"\x00" * 32 c = ciphers.Cipher(AES(b"\x00" * 32), modes.ECB()).encryptor() c.update_into(b"\x00" * 16, outbuf) 16 outbuf b'\xdc\x95\xc0x\xa2@\x89\x89\xadH\xa2\x14\x92\x84 \x87\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00' ```

This would allow immutable objects (such as bytes) to be mutated, thus violating fundamental rules of Python. This is a soundness bug -- it allows programmers to misuse an API, it cannot be exploited by attacker controlled data alone.

This now correctly raises an exception.

This issue has been present since update_into was originally introduced in cryptography 1.8.

Show details on source website

To clipboard 

{
   affected: [
      {
         package: {
            ecosystem: "PyPI",
            name: "cryptography",
         },
         ranges: [
            {
               events: [
                  {
                     introduced: "1.8",
                  },
                  {
                     fixed: "39.0.1",
                  },
               ],
               type: "ECOSYSTEM",
            },
         ],
      },
   ],
   aliases: [
      "CVE-2023-23931",
   ],
   database_specific: {
      cwe_ids: [
         "CWE-754",
      ],
      github_reviewed: true,
      github_reviewed_at: "2023-02-07T20:54:10Z",
      nvd_published_at: "2023-02-07T21:15:00Z",
      severity: "MODERATE",
   },
   details: "Previously, `Cipher.update_into` would accept Python objects which implement the buffer protocol, but provide only immutable buffers:\n\n```pycon\n>>> outbuf = b\"\\x00\" * 32\n>>> c = ciphers.Cipher(AES(b\"\\x00\" * 32), modes.ECB()).encryptor()\n>>> c.update_into(b\"\\x00\" * 16, outbuf)\n16\n>>> outbuf\nb'\\xdc\\x95\\xc0x\\xa2@\\x89\\x89\\xadH\\xa2\\x14\\x92\\x84 \\x87\\x00\\x00\\x00\\x00\\x00\\x00\\x00\\x00\\x00\\x00\\x00\\x00\\x00\\x00\\x00\\x00'\n```\n\nThis would allow immutable objects (such as `bytes`) to be mutated, thus violating fundamental rules of Python. This is a soundness bug -- it allows programmers to misuse an API, it cannot be exploited by attacker controlled data alone.\n\nThis now correctly raises an exception.\n\nThis issue has been present since `update_into` was originally introduced in cryptography 1.8.",
   id: "GHSA-w7pp-m8wf-vj6r",
   modified: "2024-09-13T20:07:50Z",
   published: "2023-02-07T20:54:10Z",
   references: [
      {
         type: "WEB",
         url: "https://github.com/pyca/cryptography/security/advisories/GHSA-w7pp-m8wf-vj6r",
      },
      {
         type: "ADVISORY",
         url: "https://nvd.nist.gov/vuln/detail/CVE-2023-23931",
      },
      {
         type: "WEB",
         url: "https://github.com/pyca/cryptography/pull/8230",
      },
      {
         type: "WEB",
         url: "https://github.com/pyca/cryptography/commit/d6951dca25de45abd52da51b608055371fbcde4e",
      },
      {
         type: "PACKAGE",
         url: "https://github.com/pyca/cryptography",
      },
      {
         type: "WEB",
         url: "https://github.com/pypa/advisory-database/tree/main/vulns/cryptography/PYSEC-2023-11.yaml",
      },
   ],
   schema_version: "1.4.0",
   severity: [
      {
         score: "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L",
         type: "CVSS_V3",
      },
      {
         score: "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N",
         type: "CVSS_V4",
      },
   ],
   summary: "Cipher.update_into can corrupt memory if passed an immutable python object as the outbuf",
}


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