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CVE-2026-31958

CVE-2026-31958 · Tornado has a DoS due to too many multipart parts

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

Tornado is a Python web framework and asynchronous networking library. In versions of Tornado prior to 6.5.5, the only limit on the number of parts in multipart/form-data is the max_body_size setting (default 100MB). Since parsing occurs synchronously on the main thread, this creates the possibility of denial-of-service due to the cost of parsing very large multipart bodies with many parts. This vulnerability is fixed in 6.5.5.

CVSS 8.7 · High · EPSS 0.4% · Fix available

Published
Updated

Stack: system · python

Affected products and versions

  • tornado

    Versions
    • < 6.5.5: Affected

    No fix published

  • python-tornado Debian:12

    Versions
    • 6.2.0-3
    • 6.2.0-3+deb12u1
    • 6.2.0-3+deb12u2
    • 6.2.0-3+deb12u3
    • 6.2.0-3+deb12u4
    • 6.3.2-1
    • 6.4.0-1
    • 6.4.0-2
    • 6.4.1-1
    • 6.4.1-2
    • 6.4.1-3
    • 6.4.2-1
    • 6.4.2-2
    • 6.4.2-3
    • 6.5.2-1
    • 6.5.2-2
    • 6.5.2-3
    • 6.5.4-0.1
    • 6.5.4-1
    • 6.5.5-1
    • 6.5.5-2
    • 6.5.5-3
    • 6.5.5-4
    • 6.5.5-5
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • python-tornado Debian:13

    Versions
    • 6.4.2-3
    • 6.4.2-3+deb13u1
    • 6.4.2-3+deb13u2
    • 6.5.2-1
    • 6.5.2-2
    • 6.5.2-3
    • 6.5.4-0.1
    • 6.5.4-1
    • 6.5.5-1
    • 6.5.5-2
    • 6.5.5-3
    • 6.5.5-4
    • 6.5.5-5
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • python-tornado Debian:14

    Versions
    • 6.4.2-3
    • 6.5.2-1
    • 6.5.2-2
    • 6.5.2-3
    • 6.5.4-0.1
    • 6.5.4-1
    Affected ranges
    • ECOSYSTEM: < 6.5.5-1

    Update to 6.5.5-1

  • tornado PyPI

    Versions
    • 0.2
    • 1.0
    • 1.1
    • 1.1.1
    • 1.2
    • 1.2.1
    • 2.0
    • 2.1
    • 2.1.1
    • 2.2
    • 2.2.1
    • 2.3
    • 2.4
    • 2.4.1
    • 3.0
    • 3.0.1
    • 3.0.2
    • 3.1
    • 3.1.1
    • 3.2
    • 3.2.1
    • 3.2.2
    • 4.0
    • 4.0.1
    • 4.0.2
    • 4.1
    • 4.1b2
    • 4.2
    • 4.2.1
    • 4.2b1
    • 4.3
    • 4.3b1
    • 4.3b2
    • 4.4
    • 4.4.1
    • 4.4.2
    • 4.4.3
    • 4.4b1
    • 4.5
    • 4.5.1
    • 4.5.2
    • 4.5.3
    • 4.5b1
    • 4.5b2
    • 5.0
    • 5.0.1
    • 5.0.2
    • 5.0a1
    • 5.0b1
    • 5.1
    • 5.1.1
    • 5.1b1
    • 6.0
    • 6.0.1
    • 6.0.2
    • 6.0.3
    • 6.0.4
    • 6.0a1
    • 6.0b1
    • 6.1
    • 6.1b1
    • 6.1b2
    • 6.2
    • 6.2b1
    • 6.2b2
    • 6.3
    • 6.3.1
    • 6.3.2
    • 6.3.3
    • 6.3b1
    • 6.4
    • 6.4.1
    • 6.4.2
    • 6.4b1
    • 6.5
    • 6.5.1
    • 6.5.2
    • 6.5.3
    • 6.5.4
    • 6.5b1
    Affected ranges
    • ECOSYSTEM: < 6.5.5

    Update to 6.5.5

  • python-tornado Ubuntu:Pro:16.04:LTS

    Versions
    • 4.2.1-1ubuntu2
    • 4.2.1-1ubuntu3
    • 4.2.1-1ubuntu3.1
    • 4.2.1-1ubuntu3.1+esm1
    • 4.2.1-1ubuntu3.1+esm2
    Affected ranges
    • ECOSYSTEM: < 4.2.1-1ubuntu3.1+esm3

    Update to 4.2.1-1ubuntu3.1+esm3

  • python-tornado Ubuntu:Pro:18.04:LTS

    Versions
    • 4.5.1-2.1~build2
    • 4.5.2-1
    • 4.5.3-1
    • 4.5.3-1ubuntu0.1
    • 4.5.3-1ubuntu0.2
    • 4.5.3-1ubuntu0.2+esm1
    • 4.5.3-1ubuntu0.2+esm2
    Affected ranges
    • ECOSYSTEM: < 4.5.3-1ubuntu0.2+esm3

    Update to 4.5.3-1ubuntu0.2+esm3

  • python-tornado Ubuntu:Pro:22.04:LTS

    Versions
    • 6.1.0-1build1
    • 6.1.0-2
    • 6.1.0-3
    • 6.1.0-3build1
    • 6.1.0-3ubuntu0.1~esm1
    • 6.1.0-3ubuntu0.1~esm2
    • 6.1.0-3ubuntu0.1~esm4
    Affected ranges
    • ECOSYSTEM: < 6.1.0-3ubuntu0.1~esm5

    Update to 6.1.0-3ubuntu0.1~esm5

  • python-tornado Ubuntu:24.04:LTS

    Versions
    • 6.3.2-1
    • 6.4.0-0ubuntu1
    • 6.4.0-1
    • 6.4.0-1build1
    • 6.4.0-1ubuntu0.1
    • 6.4.0-1ubuntu0.2
    • 6.4.0-1ubuntu0.4
    Affected ranges
    • ECOSYSTEM: < 6.4.0-1ubuntu0.5

    Update to 6.4.0-1ubuntu0.5

  • python-tornado Ubuntu:25.10

    Versions
    • 6.4.2-1
    • 6.4.2-2
    • 6.4.2-2ubuntu1
    • 6.4.2-3
    • 6.4.2-3ubuntu0.2
    Affected ranges
    • ECOSYSTEM: < 6.4.2-3ubuntu0.3

    Update to 6.4.2-3ubuntu0.3

  • python-tornado Ubuntu:26.04:LTS

    Versions
    • 6.4.2-3
    • 6.5.2-3
    • 6.5.4-0.1
    Affected ranges
    • ECOSYSTEM: < 6.5.4-0.1ubuntu0.1

    Update to 6.5.4-0.1ubuntu0.1

Original sources

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