CVE-2026-59884: pyasn1 is a generic ASN.1 library for Python
Affects pyasn1Source GCVE Database
Not known to be exploited · CVSS 7.5 High · fixed in 0.4.8-1ubuntu0.3 : patch pyasn1 soon.
Data as of 10 Nov 2026, 06:10 UTC
- Patch
- Available – fixed in 0.4.8-1ubuntu0.3, 0.4.8-4ubuntu0.3, 0.6.3-1ubuntu0.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 14 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 9 Nov 2026.
What to do
Upgrade the Ubuntu pyasn1 to 0.4.8-1ubuntu0.3 (package) or 0.4.8-4ubuntu0.3 (package) or 0.6.3-1ubuntu0.1 (package).
Patches and advisories
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSpyasn1pkg:deb/ubuntu/pyasn1?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSpyasn1pkg:deb/ubuntu/pyasn1?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 22.04 LTSpyasn1pkg:deb/ubuntu/pyasn1?arch=source&distro=jammyOther threats | Affected
| Fixed in
|
Ubuntu Pro 20.04 LTSpyasn1pkg:deb/ubuntu/pyasn1?arch=source&distro=esm-infra/focalOther threats | Affected
| Fixed in– |
Ubuntu Pro 18.04 LTSpyasn1pkg:deb/ubuntu/pyasn1?arch=source&distro=esm-infra/bionicOther threats | Affected
| Fixed in– |
Ubuntu Pro 16.04 LTSpyasn1pkg:deb/ubuntu/pyasn1?arch=source&distro=esm-infra-legacy/xenialOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
This vulnerability is fixed in pyasn1 version 0.6.4 and in the patched Ubuntu package versions 0.4.8-1ubuntu0.3, 0.4.8-4ubuntu0.3, and 0.6.3-1ubuntu0.1. Users should update to these fixed versions or later to remediate the issue. Standard system updates applying these package versions will address the vulnerability. No additional mitigation is required if these updates are applied.
Description
pyasn1 versions prior to 0.6.4 contain a vulnerability in the BER decoder used by CER and DER codecs, where long-form tag identifiers are parsed without an upper bound on tag ID size. This flaw allows crafted ASN.1 input to cause excessive CPU consumption and trigger unhandled exceptions in Python 3.11+. The issue affects applications decoding untrusted BER, CER, or DER data and is fixed in version 0.6.4.
References
- ubuntu.com/security/CVE-2026-59884 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-59884 (opens in a new tab)
- github.com/pyasn1/pyasn1/security/advisories/GHSA-m4p7-r5rc-7g4j (opens in a new tab)
- github.com/pyasn1/pyasn1/releases/tag/v0.6.4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8712-1 (opens in a new tab)