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 Details
- CVSS 3.1 Base Score: 7.5
- CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade python3-pyasn1Upgrade python3-pyasn1-modulesUpgrade python2-pyasn1Upgrade python2-pyasn1-modules | Aug 5, 2026 | Aug 5, 2026 |
| Debian | — | Upgrade pyasn1 | Sep 21, 2026 | Jul 14, 2026 |
| Redhat_linux | — | No solution exists | Jul 20, 2026 | Jul 14, 2026 |
| Ubuntu | — | Upgrade python3-pyasn1 | Sep 2, 2026 | Sep 1, 2026 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | Aug 10, 2026 | Jul 14, 2026 |
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