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VulnerabilityPublished Updated

CVE-2026-59884: pyasn1 is a generic ASN.1 library for Python

Affects pyasn1Source GCVE Database

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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

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
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:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 14 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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).

Affected software

ProductAffectedFixed in
Ubuntu 26.04 LTSpyasn1pkg:deb/ubuntu/pyasn1?arch=source&distro=resoluteOther threatsAffected
  • <0.6.3-1ubuntu0.1
Fixed in
  • 0.6.3-1ubuntu0.1
Ubuntu 24.04 LTSpyasn1pkg:deb/ubuntu/pyasn1?arch=source&distro=nobleOther threatsAffected
  • <0.4.8-4ubuntu0.3
Fixed in
  • 0.4.8-4ubuntu0.3
Ubuntu 22.04 LTSpyasn1pkg:deb/ubuntu/pyasn1?arch=source&distro=jammyOther threatsAffected
  • <0.4.8-1ubuntu0.3
Fixed in
  • 0.4.8-1ubuntu0.3
Ubuntu Pro 20.04 LTSpyasn1pkg:deb/ubuntu/pyasn1?arch=source&distro=esm-infra/focalOther threatsAffected
  • 0.4.2-3 – 0.4.2-3ubuntu0.20.04.1~esm2
4 affected builds
Fixed in–
Ubuntu Pro 18.04 LTSpyasn1pkg:deb/ubuntu/pyasn1?arch=source&distro=esm-infra/bionicOther threatsAffected
  • 0.1.9-2 – 0.4.2-3ubuntu0.18.04.1~esm2
4 affected builds
Fixed in–
Ubuntu Pro 16.04 LTSpyasn1pkg:deb/ubuntu/pyasn1?arch=source&distro=esm-infra-legacy/xenialOther threatsAffected
  • 0.1.8-2 – 0.1.9-1ubuntu0.1~esm2
4 affected builds
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

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