Medium 5.1Published May 28, 2026

CVE-2026-48156pypdf: Possible long runtimes for zero-only width values in cross-reference streams

Updated under an hour ago (Oct 27, 2026, 11:50 AM ET)

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Every CVE for py-pdf pypdf

Exploited in the last 30 days

pypdf is a free and open-source pure-python PDF library. Prior to 6.12.0, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires cross-reference streams with /W [0 0 0] values and large /Size values. This vulnerability is fixed in 6.12.0.

CVSS: 5.1 MEDIUM (v4.0, CNA)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
Weakness (CWE): CWE-834
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: May 29, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

py-pdf pypdf py_pdf:pypdf (from the name)	before 6.12.0	CNA record
pypdf_project pypdf pypdf_project:pypdf	before 6.12.0	NVD

References

References

https://github.com/py-pdf/pypdf/security/advisories/GHSA-248m-82v9-q6g6	x-refsource-confirm, patch, vendor-advisory
https://github.com/py-pdf/pypdf/pull/3791	x-refsource-misc, issue-tracking, patch
https://github.com/py-pdf/pypdf/releases/tag/6.12.0	x-refsource-misc, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.