{"id":"PYSEC-2026-1837","summary":"PyPDF2 quadratic runtime with malformed PDF missing xref marker","details":"### Impact\nAn attacker who uses this vulnerability can craft a PDF which leads to unexpected long runtime.\nThis quadratic runtime blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage.\n\n### Patches\nhttps://github.com/py-pdf/pypdf/pull/808\n\n### Workarounds\n_Is there a way for users to fix or remediate the vulnerability without upgrading?_\n\n### References\n* [PyPDF2 PR #808](https://github.com/py-pdf/pypdf/pull/808)\n* [PyPDF2 Issue #582](https://github.com/py-pdf/pypdf/issues/582)","aliases":["CVE-2023-36810","GHSA-jrm6-h9cq-8gqw"],"modified":"2026-07-07T17:46:59.524042100Z","published":"2026-07-07T11:45:19.715500Z","references":[{"type":"WEB","url":"https://github.com/py-pdf/pypdf/security/advisories/GHSA-jrm6-h9cq-8gqw"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-36810"},{"type":"WEB","url":"https://github.com/py-pdf/pypdf/issues/582"},{"type":"WEB","url":"https://github.com/py-pdf/pypdf/pull/808"},{"type":"FIX","url":"https://github.com/py-pdf/pypdf/commit/c6c56f550bb384e05f0139c796ba1308837d6373"},{"type":"PACKAGE","url":"https://github.com/py-pdf/pypdf"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2023/07/msg00019.html"},{"type":"PACKAGE","url":"https://pypi.org/project/pypdf2"},{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-jrm6-h9cq-8gqw"}],"affected":[{"package":{"name":"pypdf2","ecosystem":"PyPI","purl":"pkg:pypi/pypdf2"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.27.9"}]}],"versions":["1.15","1.16","1.17","1.18","1.19","1.20","1.21","1.22","1.23","1.24","1.25","1.25.1","1.26.0","1.27.0","1.27.1","1.27.2","1.27.3","1.27.4","1.27.5","1.27.6","1.27.7","1.27.8"],"database_specific":{"source":"https://github.com/pypa/advisory-database/blob/main/vulns/pypdf2/PYSEC-2026-1837.yaml"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}