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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
None
No privileges needed
User Interaction
Passive
Minimal interaction
Impact Assessment
Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service
CVSS Vector v4.0
Weakness Type (CWE)
References 4
https://github.com/py-pdf/pypdf/commit/a93fe3a901fd00af38f0a105c3ba7175fa72dcb4
security-advisories@github.com
https://github.com/py-pdf/pypdf/pull/4269
security-advisories@github.com
https://github.com/py-pdf/pypdf/releases/tag/6.21.3
security-advisories@github.com
https://github.com/py-pdf/pypdf/security/advisories/GHSA-x3rh-gjgm-fmqc
security-advisories@github.com