pyasn1 BER/CER/DER decoder denial of service via unbounded long-form tag IDs (pyasn1 pyasn1)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.62 % · percentile 50 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Analyzed
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.
Weaknesses (CWE)
- CWE-400 — Uncontrolled Resource Consumption
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | GitHub_M |
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | NVD · security-advisories@github.com (Secondary) |
Advisories
- GHSA-m4p7-r5rc-7g4j — pyasn1 BER/CER/DER decoder denial of service via unbounded long-form tag IDs
- PYSEC-2026-3455 — 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 continuatio
European references
- ENISA EUVD · EUVD-2026-43956
- GCVE · GCVE-0-2026-59884
CERT-FR advisories
- CERTFR-2026-AVI-1385 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1291 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1249 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
Affected configurations (NVD CPE)
cpe:2.3:a:pyasn1:pyasn1:*:*:*:*:*:python:*:*< 0.6.4
Affected products
| Product | Versions |
|---|---|
| pyasn1 · pyasn1 | affected < 0.6.4 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |