Vulnerability Description
pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER decoder shared by the CER and DER codecs parses long-form tags by accumulating continuation octets without an upper bound on the tag ID size, allowing a crafted input to force construction of an arbitrarily large integer with CPU cost growing quadratically and to trigger unhandled ValueError exceptions in Python 3.11+ error formatting paths. Any application decoding untrusted BER, CER, or DER input is affected. This issue is fixed in version 0.6.4.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Pyasn1 | Pyasn1 | < 0.6.4 |
Related Weaknesses (CWE)
References
- https://github.com/pyasn1/pyasn1/commit/628e36ecbb5277a3f01572ce418ef54271b165a5Patch
- https://github.com/pyasn1/pyasn1/releases/tag/v0.6.4Release Notes
- https://github.com/pyasn1/pyasn1/security/advisories/GHSA-m4p7-r5rc-7g4jThird Party Advisory
FAQ
What is CVE-2026-59884?
CVE-2026-59884 is a vulnerability with a CVSS score of 7.5 (HIGH). pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER decoder shared by the CER and DER codecs parses long-form tags by accumulating continuation octets without an upper bound on the t...
How severe is CVE-2026-59884?
CVE-2026-59884 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-59884?
Check the references section above for vendor advisories and patch information. Affected products include: Pyasn1 Pyasn1.