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CVE-2026-55200

CVE-2026-55200 · libssh2 - Out-of-Bounds Write via Unchecked packet_length in transport.c

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

libssh2 1.11.1, fixed in commit 97acf3d, contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field. Remote attackers can send crafted SSH packets with excessively large packet_length values to corrupt heap memory and achieve remote code execution.

CVSS 9.2 · Critical · EPSS 4.0% · Fix available

Published
Updated

Stack: system

Affected products and versions

  • libssh2

    Versions
    • 1.11.1: Affected (semver)
    • ≥ 1c3f1b7da588f2652260285529ec3c1f1125eb4e, < 97acf3dfda80c91c3a8c9f2372546301d4a1a7a8: Affected (git)

    Update to 97acf3dfda80c91c3a8c9f2372546301d4a1a7a8

  • libssh2 Debian:13

    Versions
    • 1.11.1-1
    Affected ranges
    • ECOSYSTEM: < 1.11.1-1+deb13u1

    Update to 1.11.1-1+deb13u1

  • libssh2 Debian:14

    Versions
    • 1.11.1-1
    • 1.11.1-2
    • 1.11.1-3
    Affected ranges
    • ECOSYSTEM: < 1.11.1-4

    Update to 1.11.1-4

  • libssh2 Ubuntu:25.10

    Versions
    • 1.11.1-1
    • 1.11.1-1build1
    • 1.11.1-1ubuntu0.25.10.1
    Affected ranges
    • ECOSYSTEM: < 1.11.1-1ubuntu0.25.10.2

    Update to 1.11.1-1ubuntu0.25.10.2

  • libssh2 Ubuntu:26.04:LTS

    Versions
    • 1.11.1-1build1
    • 1.11.1-1build2
    • 1.11.1-1ubuntu0.26.04.1
    Affected ranges
    • ECOSYSTEM: < 1.11.1-1ubuntu0.26.04.2

    Update to 1.11.1-1ubuntu0.26.04.2

Original sources

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