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VulnerabilityPublished Updated

CVE-2026-59886: 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 later. Ubuntu users should update to the fixed package versions: 0.4.8-1ubuntu0.3, 0.4.8-4ubuntu0.3, or 0.6.3-1ubuntu0.1 depending on their Ubuntu release. Applying standard system updates will install these fixes. No additional mitigation is required once patched.

Description

pyasn1 versions prior to 0.6.4 contain a vulnerability in the univ.Real type where conversion of decoded REAL values to Python float types can consume excessive CPU and memory. This occurs because a BER, CER, or DER encoded REAL value with a very large exponent triggers expensive big-integer exponentiation during float conversion operations, potentially causing application hangs. The issue is fixed in version 0.6.4.

References

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