Low severity · published May 28, 2026
CVE-2026-48156
pypdf: Possible long runtimes for zero-only width values in cross-reference streams
3.3
CVSS
0.1%
EPSS
No
On KEV
Description
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 vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.1% · higher than 2% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
PY
pypdf · py-pdf
< 6.12.0 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-48156
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-48156
Issue Tracking
https://github.com/py-pdf/pypdf/pull/3791
Release Notes
https://github.com/py-pdf/pypdf/releases/tag/6.12.0
Patch
https://github.com/py-pdf/pypdf/security/advisories/GHSA-248m-82v9-q6g6
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