{"id":"CVE-2025-66019","aliases":["GHSA-m449-cwjh-6pw7","PYSEC-2026-1832"],"url":"https://o3.security/vulnerability/CVE-2025-66019","summary":"pypdf manipulated LZWDecode streams can exhaust RAM","details":"### Impact\n\nAn attacker who uses this vulnerability can craft a PDF which leads to a memory usage of up to 1 GB per stream. This requires parsing the content stream of a page using the LZWDecode filter.\n\nThis is a follow up to [GHSA-jfx9-29x2-rv3j](https://github.com/py-pdf/pypdf/security/advisories/GHSA-jfx9-29x2-rv3j) to align the default limit with the one for *zlib*.\n\n### Patches\nThis has been fixed in [pypdf==6.4.0](https://github.com/py-pdf/pypdf/releases/tag/6.4.0).\n\n### Workarounds\nIf users cannot upgrade yet, use the line below to overwrite the default in their code:\n\n```python\npypdf.filters.LZW_MAX_OUTPUT_LENGTH = 75_000_000\n```","published":"2025-11-25T23:38:12.473Z","modified":"2026-08-12T03:51:24.918591649Z","cvss":null,"epss":{"score":0.00361,"percentile":0.28793,"asOf":"2026-08-24"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"pypdf","fixedVersion":"6.4.0"}],"fix":{"url":"https://github.com/py-pdf/pypdf/commit/96186725e5e6f237129a58a97cd19204a9ce40b2","label":"py-pdf/pypdf@9618672"},"references":[{"type":"WEB","url":"https://aydinnyunus.github.io/2025/12/20/cve-2025-66019-pypdf-lzw-dos/"},{"type":"WEB","url":"https://github.com/py-pdf/pypdf/releases/tag/6.4.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/66xxx/CVE-2025-66019.json"},{"type":"ADVISORY","url":"https://github.com/py-pdf/pypdf/security/advisories/GHSA-m449-cwjh-6pw7"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-66019"},{"type":"FIX","url":"https://github.com/py-pdf/pypdf/commit/96186725e5e6f237129a58a97cd19204a9ce40b2"},{"type":"WEB","url":"https://github.com/py-pdf/pypdf/security/advisories/GHSA-jfx9-29x2-rv3j"},{"type":"WEB","url":"https://aydinnyunus.github.io/2025/12/20/cve-2025-66019-pypdf-lzw-dos"},{"type":"PACKAGE","url":"https://github.com/py-pdf/pypdf"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:24.918591649Z"}}