{"id":"CVE-2026-27026","title":"pypdf: pypdf: Denial of Service via malformed PDF /FlateDecode stream (CVE-2026-27026)","summary":"A flaw was found in pypdf, a pure-python PDF library. A remote attacker can exploit this vulnerability by crafting a malicious PDF file containing a malformed /FlateDecode stream. This stream, which is used for data compression within the …","severity":"medium","cvss":6.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":"CWE-1050","vendor":"Red Hat","product":"OpenShift Lightspeed","affected":["openshift_lightspeed","enterprise_linux_ai_rhel_ai 3","openshift_ai_rhoai"],"patched":["pypdf 6.7.1"],"published":"2026-02-20","updated":"2026-10-15","sourceUpdated":"2026-10-15T11:34:16+00:00","source":"CSAF","sourceUrl":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27026.json","references":[{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27026.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-27026"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2441495"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-27026"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-27026"},{"url":"https://github.com/py-pdf/pypdf/commit/7905842d833f899f1d3228af7e7467ad80277016"},{"url":"https://github.com/py-pdf/pypdf/pull/3644"},{"url":"https://github.com/py-pdf/pypdf/releases/tag/6.7.1"},{"url":"https://github.com/py-pdf/pypdf/security/advisories/GHSA-9mvc-8737-8j8h"},{"url":"https://github.com/py-pdf/pypdf"}],"tags":["csaf","vex","red-hat","osv","pip"],"epss":0.00191,"epssPercentile":0.08644,"aliases":["GHSA-9mvc-8737-8j8h","PYSEC-2026-3015"],"ecosystem":"pip","ingestedAt":"2026-07-13T18:57:56.017Z","slug":"CVE-2026-27026","body":"## Overview\n\nA flaw was found in pypdf, a pure-python PDF library. A remote attacker can exploit this vulnerability by crafting a malicious PDF file containing a malformed /FlateDecode stream. This stream, which is used for data compression within the PDF, can cause excessively long processing times when decompressed byte-by-byte. This leads to a Denial of Service (DoS), making the affected system or application unresponsive.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: OpenShift Lightspeed, Red Hat Enterprise Linux AI (RHEL AI) 3, Red Hat OpenShift AI (RHOAI) · no fix planned: OpenShift Lightspeed, Red Hat Enterprise Linux AI (RHEL AI) 3, Red Hat OpenShift AI (RHOAI) · updated 2026-10-15 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27026.json)\n\n**pypdf: pypdf: Denial of Service via malformed PDF /FlateDecode stream** — rated Moderate by Red Hat. Released 2026-02-20, updated 2026-10-15.\n\nAffected:\n\n- OpenShift Lightspeed\n- Red Hat Enterprise Linux AI (RHEL AI) 3\n- Red Hat OpenShift AI (RHOAI)\n\nNo fix planned:\n\n- OpenShift Lightspeed\n- Red Hat Enterprise Linux AI (RHEL AI) 3\n- Red Hat OpenShift AI (RHOAI)\n\n## Remediation\n\nFix deferred\n\nWorkarounds / mitigations:\n\n- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.\n\n## Package advisory (CVE-2026-27026)\n\nAffected packages:\n\n- `pypdf < 6.7.1`\n\nPatched in:\n\n- `pypdf 6.7.1`\n\nSource: https://osv.dev/vulnerability/GHSA-9mvc-8737-8j8h","depth":"sunlit","depthScore":36,"depthScoreParts":{"impact":35.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":222188,"id":"CVE-2026-27026","ts":1792065058173,"field":"cvss","old":null,"new":"6.5"}]}