High severity · published Feb 26, 2026
CVE-2026-27888
pypdf: Manipulated FlateDecode XFA streams can exhaust RAM
7.5
CVSS
0.4%
EPSS
No
On KEV
Description
pypdf is a free and open-source pure-python PDF library. Prior to 6.7.3, an attacker who uses this vulnerability can craft a PDF which leads to the RAM being exhausted. This requires accessing the `xfa` property of a reader or writer and the corresponding stream being compressed using `/FlateDecode`. This has been fixed in pypdf 6.7.3. As a workaround, apply the patch manually.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 34% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
PY
pypdf · py-pdf
< 6.7.3 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27888
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-27888
Patch
https://github.com/py-pdf/pypdf/commit/7a4c8246ed48d9d328fb596942271da47b6d109c
Issue Tracking
https://github.com/py-pdf/pypdf/pull/3658
Product
https://github.com/py-pdf/pypdf/releases/tag/6.7.3
Patch
https://github.com/py-pdf/pypdf/security/advisories/GHSA-x7hp-r3qg-r3cj
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