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Vulnerability · Published Jan 27, 2026 · Assigned by GitHub_M

CVE-2026-24688pypdf has possible Infinite Loop when processing outlines/bookmarks

Medium 5.1

In plain English

A medium-severity infinite loop in pypdf from py-pdf. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 39% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)5.1Medium
Exploit odds (30 days)0.4%top 61.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack tooling1Public PoC

Official description

pypdf is a free and open-source pure-python PDF library. An attacker who uses an infinite loop vulnerability that is present in versions prior to 6.6.2 can craft a PDF which leads to an infinite loop. This requires accessing the outlines/bookmarks. This has been fixed in pypdf 6.6.2. If projects cannot upgrade yet, consider applying the changes from PR #3610 manually.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12pypdfno fix listedDEBIAN-CVE-2026-24688
Debian:13pypdfno fix listedDEBIAN-CVE-2026-24688
Debian:14pypdf6.9.0-1DEBIAN-CVE-2026-24688
Debian:12pypdf2no fix listedDEBIAN-CVE-2026-24688
PyPIpypdf6.6.2GHSA-2q4j-m29v-hq73
PyPIpypdf6.6.2PYSEC-2026-1827
Ubuntu:24.04:LTSpypdfno fix listedUBUNTU-CVE-2026-24688
Ubuntu:25.10pypdfno fix listedUBUNTU-CVE-2026-24688
Ubuntu:26.04:LTSpypdfno fix listedUBUNTU-CVE-2026-24688
Ubuntu:26.10pypdfno fix listedUBUNTU-CVE-2026-24688
Ubuntu:22.04:LTSpypdf2no fix listedUBUNTU-CVE-2026-24688
Ubuntu:24.04:LTSpypdf2no fix listedUBUNTU-CVE-2026-24688

Affected products (as reported)

VendorProductVersions
py-pdf pypdf < 6.6.2

Weakness: CWE-835 · Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

References