High severity · published Oct 29, 2026
CVE-2026-119209
pypdf: Possible large memory usage when parsing cross-reference streams
New
7.1
CVSS
–
EPSS
No
On KEV
Description
pypdf is a free and open-source pure-python PDF library. Prior to 6.21.3, pypdf can consume excessive memory while opening a crafted PDF containing cross-reference streams that declare very large entry counts. Highly compressible streams and /Prev chains can multiply the number of parsed entries across a document, while negative /Index counts can bypass the existing per-stream clamp. This issue is fixed in version 6.21.3.
Exploitation
Is it being used?
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
PY
pypdf · py-pdf
< 6.21.3 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-119209
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-119209
github.com
https://github.com/py-pdf/pypdf/commit/a93fe3a901fd00af38f0a105c3ba7175fa72dcb4
github.com
https://github.com/py-pdf/pypdf/pull/4269
github.com
https://github.com/py-pdf/pypdf/releases/tag/6.21.3
github.com
https://github.com/py-pdf/pypdf/security/advisories/GHSA-x3rh-gjgm-fmqc
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