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Vulnerability · Published Mar 6, 2026 · Assigned by GitHub_M

CVE-2026-28804pypdf: Inefficient decoding of ASCIIHexDecode streams

Medium 6.9

In plain English

A medium-severity security flaw 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). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)6.9Medium
Exploit odds (30 days)0.4%top 61.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

pypdf is a free and open-source pure-python PDF library. Prior to version 6.7.5, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires accessing a stream which uses the /ASCIIHexDecode filter. This issue has been patched in version 6.7.5.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12pypdfno fix listedDEBIAN-CVE-2026-28804
Debian:13pypdfno fix listedDEBIAN-CVE-2026-28804
Debian:14pypdf6.9.0-1DEBIAN-CVE-2026-28804
Debian:12pypdf2no fix listedDEBIAN-CVE-2026-28804
PyPIpypdf6.7.5PYSEC-2026-3014
PyPIpypdf6.7.5GHSA-9m86-7pmv-2852
Ubuntu:24.04:LTSpypdfno fix listedUBUNTU-CVE-2026-28804
Ubuntu:25.10pypdfno fix listedUBUNTU-CVE-2026-28804
Ubuntu:26.04:LTSpypdfno fix listedUBUNTU-CVE-2026-28804
Ubuntu:26.10pypdfno fix listedUBUNTU-CVE-2026-28804

Affected products (as reported)

VendorProductVersions
py-pdf pypdf < 6.7.5

Weakness: CWE-407 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

References