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CVE-2026-54911

CVE-2026-54911 · UltraJSON: Malformed/Truncated UTF-8 Accepted and Silently Rewritten in ujson.dumps()

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

This page shows selected source facts. See the linked advisories for the complete description and affected versions.

UltraJSON is a fast JSON encoder and decoder written in pure C with bindings for Python 3.7+. Prior to 5.13.0, ujson.dumps() (or ujson.dump() or ujson.encode()) have a reject_bytes=False option. When set, they may accept malformed or truncated UTF-8 byte sequences, silently rewriting them into different Unicode characters instead of rejecting them. This leads to input validation bypass and data integrity issues. This vulnerability is fixed in 5.13.0.

CVSS 6.5 · Medium · EPSS 0.4% · Fix available

Published
Updated

Stack: system · python

Affected products and versions

  • ultrajson

    Versions
    • < 5.13.0: Affected

    No fix published

  • ujson Debian:12

    Versions
    • 5.10.0-1
    • 5.11.0-1
    • 5.11.0-2
    • 5.11.0-3
    • 5.13.0-1
    • 5.7.0-1
    • 5.8.0-1
    • 5.9.0-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • ujson Debian:13

    Versions
    • 5.10.0-1
    • 5.11.0-1
    • 5.11.0-2
    • 5.11.0-3
    • 5.13.0-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • ujson Debian:14

    Versions
    • 5.10.0-1
    • 5.11.0-1
    • 5.11.0-2
    • 5.11.0-3
    Affected ranges
    • ECOSYSTEM: < 5.13.0-1

    Update to 5.13.0-1

  • ujson PyPI

    Versions
    • 1.15
    • 1.18
    • 1.19
    • 1.21
    • 1.22
    • 1.23
    • 1.30
    • 1.33
    • 1.34
    • 1.35
    • 1.4
    • 1.6
    • 1.8
    • 1.9
    • 2.0.0
    • 2.0.1
    • 2.0.2
    • 2.0.3
    • 3.0.0
    • 3.1.0
    • 3.2.0
    • 4.0.0
    • 4.0.1
    • 4.0.2
    • 4.1.0
    • 4.2.0
    • 4.3.0
    • 5.0.0
    • 5.1.0
    • 5.10.0
    • 5.11.0
    • 5.12.0
    • 5.12.1
    • 5.2.0
    • 5.3.0
    • 5.4.0
    • 5.5.0
    • 5.6.0
    • 5.7.0
    • 5.8.0
    • 5.9.0
    Affected ranges
    • ECOSYSTEM: < 5.13.0

    Update to 5.13.0

  • pandas Ubuntu:14.04:LTS

    Versions
    • 0.12.0-2ubuntu1
    • 0.13.1-2ubuntu1
    • 0.13.1-2ubuntu2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • collada2gltf Ubuntu:16.04:LTS

    Versions
    • 20140924-3
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • pandas Ubuntu:16.04:LTS

    Versions
    • 0.15.0-2
    • 0.15.0-2ubuntu1
    • 0.15.0-2ubuntu2
    • 0.17.1-3ubuntu2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • ujson Ubuntu:Pro:16.04:LTS

    Versions
    • 1.33-1
    • 1.33-1build1
    • 1.33-1ubuntu0.1~esm2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • collada2gltf Ubuntu:18.04:LTS

    Versions
    • 20140924-4
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • pandas Ubuntu:18.04:LTS

    Versions
    • 0.19.2-5.1ubuntu4
    • 0.22.0-2ubuntu1
    • 0.22.0-3
    • 0.22.0-4
    • 0.22.0-4ubuntu1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • ujson Ubuntu:Pro:18.04:LTS

    Versions
    • 1.35-1build2
    • 1.35-2
    • 1.35-2ubuntu0.1~esm1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • pandas Ubuntu:20.04:LTS

    Versions
    • 0.23.3+dfsg-4ubuntu1
    • 0.23.3+dfsg-4ubuntu5
    • 0.23.3+dfsg-4ubuntu6
    • 0.25.3+dfsg-4
    • 0.25.3+dfsg-4build1
    • 0.25.3+dfsg-7
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • ujson Ubuntu:Pro:20.04:LTS

    Versions
    • 1.35-3build1
    • 1.35-3build2
    • 1.35-4
    • 1.35-4build1
    • 1.35-4ubuntu0.1
    • 1.35-4ubuntu0.1+esm1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • collada2gltf Ubuntu:22.04:LTS

    Versions
    • 20140924-7build1
    • 20140924-8
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • pandas Ubuntu:22.04:LTS

    Versions
    • 1.1.5+dfsg-2
    • 1.1.5+dfsg-2ubuntu1
    • 1.3.5+dfsg-2
    • 1.3.5+dfsg-2ubuntu1
    • 1.3.5+dfsg-3
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • ujson Ubuntu:Pro:22.04:LTS

    Versions
    • 4.0.2-1
    • 4.0.2-1build1
    • 4.2.0-1
    • 5.1.0-1
    • 5.1.0-1build1
    • 5.1.0-1ubuntu0.1~esm1
    • 5.1.0-1ubuntu0.1~esm2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • pandas Ubuntu:24.04:LTS

    Versions
    • 1.5.3+dfsg-6
    • 1.5.3+dfsg-6ubuntu1
    • 1.5.3+dfsg-7ubuntu1
    • 1.5.3+dfsg-10
    • 2.1.4+dfsg-4ubuntu2
    • 2.1.4+dfsg-7
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • ujson Ubuntu:Pro:24.04:LTS

    Versions
    • 5.8.0-1
    • 5.8.0-1build1
    • 5.9.0-1
    • 5.9.0-1build1
    • 5.9.0-1ubuntu0.1~esm1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • pandas Ubuntu:25.10

    Versions
    • 2.2.3+dfsg-8build1
    • 2.2.3+dfsg-9
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • ujson Ubuntu:25.10

    Versions
    • 5.10.0-1build2
    • 5.10.0-1ubuntu0.1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • pandas Ubuntu:26.10

    Versions
    • 2.3.3+dfsg-3ubuntu1
    • 2.3.3+dfsg-3ubuntu3
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • ujson Ubuntu:26.10

    Versions
    • 5.11.0-3build1
    • 5.13.0-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • pandas Ubuntu:26.04:LTS

    Versions
    • 2.2.3+dfsg-9
    • 2.3.3+dfsg-1ubuntu1
    • 2.3.3+dfsg-3
    • 2.3.3+dfsg-3ubuntu1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

Original sources

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