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CVE-2026-119196

CVE-2026-119196 · pyasn1: Quadratic CPU consumption in constructed BIT STRING decoding

This page contains facts from public vulnerability sources. Check the original advisory before updating.

pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.5, constructed BIT STRING decoding repeatedly shifts and copies the complete bit value accumulated from earlier fragments. Attacker-controlled BER or CER input contains many constructed BIT STRING fragments; schema-driven DER also accepts a definite-length constructed BIT STRING. BitStringPayloadDecoder repeatedly calls BitString.fromOctetString with the prior bitString as prepend, shifting an ever-growing SizedInteger for each fragment and causing quadratic work. Large fragmented values can exhaust CPU during decode() without requiring later conversion or formatting. This issue is fixed in version 0.6.5.

CVSS 7.5 · High · EPSS 0.4% · Fix available

Published
Updated

Stack: system · python

Affected products and versions

  • pyasn1

    Versions
    • < 0.6.5: Affected

    No fix published

  • pyasn1 Debian:12

    Versions
    • 0.4.8-3
    • 0.4.8-3+deb12u1
    • 0.4.8-3+deb12u2
    • 0.4.8-3+deb12u3
    • 0.4.8-4
    • 0.5.1-1
    • 0.6.0-1
    • 0.6.1-1
    • 0.6.2-1
    • 0.6.2-1~bpo13+1
    • 0.6.3-1
    • 0.6.4-1
    • 0.6.4-1~bpo13+1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • pyasn1 Debian:13

    Versions
    • 0.6.1-1
    • 0.6.1-1+deb13u1
    • 0.6.1-1+deb13u2
    • 0.6.1-1+deb13u3
    • 0.6.2-1
    • 0.6.2-1~bpo13+1
    • 0.6.3-1
    • 0.6.4-1
    • 0.6.4-1~bpo13+1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • pyasn1 Debian:14

    Versions
    • 0.6.1-1
    • 0.6.2-1
    • 0.6.2-1~bpo13+1
    • 0.6.3-1
    • 0.6.4-1
    • 0.6.4-1~bpo13+1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • pyasn1 PyPI

    Versions
    • 0.0.10a
    • 0.0.11a
    • 0.0.12a
    • 0.0.13
    • 0.0.13a
    • 0.0.13b
    • 0.0.6a
    • 0.0.9a
    • 0.1.1
    • 0.1.2
    • 0.1.3
    • 0.1.4
    • 0.1.5
    • 0.1.6
    • 0.1.7
    • 0.1.8
    • 0.1.9
    • 0.2.1
    • 0.2.2
    • 0.2.3
    • 0.3.1
    • 0.3.2
    • 0.3.3
    • 0.3.4
    • 0.3.5
    • 0.3.6
    • 0.3.7
    • 0.4.1
    • 0.4.2
    • 0.4.3
    • 0.4.4
    • 0.4.5
    • 0.4.6
    • 0.4.7
    • 0.4.8
    • 0.5.0
    • 0.5.1
    • 0.6.0
    • 0.6.1
    • 0.6.2
    • 0.6.3
    • 0.6.4
    Affected ranges
    • ECOSYSTEM: < 0.6.5

    Update to 0.6.5

  • pyasn1 Ubuntu:Pro:14.04:LTS

    Versions
    • 0.1.4-0ubuntu1
    • 0.1.7-1ubuntu1
    • 0.1.7-1ubuntu2
    • 0.1.7-1ubuntu2.1
    • 0.1.7-1ubuntu2.1+esm1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • pyasn1 Ubuntu:Pro:16.04:LTS

    Versions
    • 0.1.8-2
    • 0.1.9-1
    • 0.1.9-1ubuntu0.1~esm1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • pyasn1 Ubuntu:Pro:18.04:LTS

    Versions
    • 0.1.9-2
    • 0.4.2-3
    • 0.4.2-3ubuntu0.18.04.1~esm1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • pyasn1 Ubuntu:Pro:20.04:LTS

    Versions
    • 0.4.2-3
    • 0.4.2-3build1
    • 0.4.2-3ubuntu0.20.04.1~esm1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • pyasn1 Ubuntu:22.04:LTS

    Versions
    • 0.4.8-1
    • 0.4.8-1ubuntu0.1
    • 0.4.8-1ubuntu0.2
    • 0.4.8-1ubuntu0.3
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • pyasn1 Ubuntu:24.04:LTS

    Versions
    • 0.4.8-4
    • 0.4.8-4ubuntu0.1
    • 0.4.8-4ubuntu0.2
    • 0.4.8-4ubuntu0.3
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • pyasn1 Ubuntu:26.10

    Versions
    • 0.6.3-1
    • 0.6.4-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • pyasn1 Ubuntu:26.04:LTS

    Versions
    • 0.6.1-1
    • 0.6.1-1build1
    • 0.6.2-1
    • 0.6.3-1
    • 0.6.3-1ubuntu0.1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

Original sources

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