{"id":"CVE-2023-23931","aliases":["GHSA-w7pp-m8wf-vj6r","PYSEC-2023-11"],"url":"https://o3.security/vulnerability/CVE-2023-23931","summary":"Cipher.update_into can corrupt memory in pyca cryptography","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.","published":"2023-02-07T20:54:03.628Z","modified":"2026-10-28T02:30:44.497803418Z","cvss":{"score":4.8,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L"},"epss":{"score":0.01301,"percentile":0.67827,"asOf":"2026-08-23"},"cisaKev":null,"exploitsKnown":1,"affectedPackages":[{"ecosystem":"PyPI","name":"cryptography","fixedVersion":"39.0.1"}],"fix":{"url":"https://github.com/pyca/cryptography/pull/8230/commits/94a50a9731f35405f0357fa5f3b177d46a726ab3","label":"pyca/cryptography#8230"},"references":[{"type":"WEB","url":"https://github.com/pyca/cryptography/pull/8230/commits/94a50a9731f35405f0357fa5f3b177d46a726ab3"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2024/10/msg00012.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/23xxx/CVE-2023-23931.json"},{"type":"ADVISORY","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":"ADVISORY","url":"https://security.netapp.com/advisory/ntap-20230324-0007/"},{"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"},{"type":"WEB","url":"https://security.netapp.com/advisory/ntap-20230324-0007"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-28T02:30:44.497803418Z"}}