CVE-2026-27628 PUBLISHED

pypdf has a possible infinite loop when loading circular /Prev entries in cross-reference streams

Assigner: GitHub_M
Reserved: 20.02.2026 Published: 25.02.2026 Updated: 25.02.2026

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.2, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires reading the file. This has been fixed in pypdf 6.7.2. As a workaround, one may apply the patch manually.

Metrics

CVSS 4.0

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
CVSS Score: 1.2

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	None	Confidentiality	None
Attack Complexity	Low	Integrity	None	Integrity	None
Attack Requirements	None	Availability	Low	Availability	None
Privileges Required	None
User Interaction	Active

CVSS 4.0

Product Status

Vendor	py-pdf
Product	pypdf
Versions	Version < 6.7.2 is affected

References

Problem Types

CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop') CWE