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CVE-2026-39402

CVE-2026-39402 · lxc lxc-user-nic insufficient ownership validation allows cross-tenant OVS port deletion

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

lxc is a Linux container runtime. In the setuid helper lxc-user-nic, the delete path contains a logic flaw in the find_line() function that allows an unprivileged user to delete OVS-attached network interfaces belonging to other users. When lxc-user-nic delete scans its NIC database to authorize a deletion request, the interface name comparison can set the authorization flag based on a name match alone, even when the ownership, type, and link fields in that database entry belong to a different user. The vulnerable check sits after the goto next label handling, meaning it is reachable on lines where earlier ownership checks failed or were skipped. Because nothing downstream of this authorization signal re-verifies that the matched database line actually belongs to the caller, an unprivileged attacker with a valid lxc-usernet policy entry can trigger deletion of another user's OVS port on the same bridge. This is limited to multi-tenant environments using lxc-user-nic with OpenVSwitch bridges. The impact is denial of service - one tenant can repeatedly disconnect networking from containers run by another tenant on shared infrastructure. This is patched in version 7.0.0.

CVSS 4.3 · Medium · EPSS 0.1% · Fix available

Published
Updated

Stack: system

Affected products and versions

  • lxc

    Versions
    • < 7.0.0: Affected

    No fix published

  • lxc Debian:12

    Versions
    • 1:5.0.2-1
    • 1:5.0.2-1+deb12u1
    • 1:5.0.2-1+deb12u2
    • 1:5.0.2-1+deb12u3
    Affected ranges
    • ECOSYSTEM: < 1:5.0.2-1+deb12u4

    Update to 1:5.0.2-1+deb12u4

  • lxc Debian:13

    Versions
    • 1:6.0.4-4
    • 1:6.0.4-4+deb13u1
    • 1:6.0.4-4+deb13u2
    Affected ranges
    • ECOSYSTEM: < 1:6.0.4-4+deb13u3

    Update to 1:6.0.4-4+deb13u3

  • lxc Debian:14

    Versions
    • 1:6.0.4-4
    • 1:6.0.5-1
    • 1:6.0.5-2
    • 1:6.0.6-1
    • 1:6.0.6-2
    • 1:6.0.6-3
    Affected ranges
    • ECOSYSTEM: < 1:7.0.0-1

    Update to 1:7.0.0-1

  • lxc Ubuntu:14.04:LTS

    Versions
    • 1.0.0~alpha1-0ubuntu11
    • 1.0.0~alpha2-0ubuntu1
    • 1.0.0~alpha2-0ubuntu3
    • 1.0.0~alpha2-0ubuntu4
    • 1.0.0~alpha2-0ubuntu5
    • 1.0.0~alpha2-0ubuntu6
    • 1.0.0~alpha3-0ubuntu1
    • 1.0.0~alpha3-0ubuntu2
    • 1.0.0~alpha3-0ubuntu3
    • 1.0.0~alpha3-0ubuntu4
    • 1.0.0~alpha3-0ubuntu5
    • 1.0.0~alpha3-0ubuntu6
    • 1.0.0~alpha3-0ubuntu7
    • 1.0.0~alpha3-0ubuntu8
    • 1.0.0~beta1-0ubuntu1
    • 1.0.0~beta1-0ubuntu2
    • 1.0.0~beta1-0ubuntu3
    • 1.0.0~beta2-0ubuntu1
    • 1.0.0~beta2-0ubuntu2
    • 1.0.0~beta3-0ubuntu1
    • 1.0.0~beta4-0ubuntu1
    • 1.0.0~beta4-0ubuntu2
    • 1.0.0~rc1-0ubuntu2
    • 1.0.0~rc3-0ubuntu1
    • 1.0.0~rc4-0ubuntu1
    • 1.0.0-0ubuntu1
    • 1.0.0-0ubuntu2
    • 1.0.0-0ubuntu3
    • 1.0.0-0ubuntu4
    • 1.0.1-0ubuntu1
    • 1.0.2-0ubuntu1
    • 1.0.2-0ubuntu2
    • 1.0.3-0ubuntu1
    • 1.0.3-0ubuntu2
    • 1.0.3-0ubuntu3
    • 1.0.4-0ubuntu0.1
    • 1.0.5-0ubuntu0.1
    • 1.0.6-0ubuntu0.1
    • 1.0.7-0ubuntu0.1
    • 1.0.7-0ubuntu0.2
    • 1.0.7-0ubuntu0.5
    • 1.0.7-0ubuntu0.6
    • 1.0.7-0ubuntu0.7
    • 1.0.7-0ubuntu0.9
    • 1.0.7-0ubuntu0.10
    • 1.0.8-0ubuntu0.3
    • 1.0.8-0ubuntu0.4
    • 1.0.9-0ubuntu2
    • 1.0.9-0ubuntu3
    • 1.0.10-0ubuntu1
    • 1.0.10-0ubuntu1.1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • lxc Ubuntu:Pro:18.04:LTS

    Versions
    • 2.1.0-0ubuntu1
    • 2.1.1-0ubuntu1
    • 3.0.0~beta1-0ubuntu3
    • 3.0.0~beta2-0ubuntu2
    • 3.0.0~beta3-0ubuntu1
    • 3.0.0~beta4-0ubuntu1
    • 3.0.0-0ubuntu1
    • 3.0.0-0ubuntu2
    • 3.0.1-0ubuntu1~18.04.1
    • 3.0.1-0ubuntu1~18.04.2
    • 3.0.2-0ubuntu1~18.04.1
    • 3.0.3-0ubuntu1~18.04.1
    • 3.0.3-0ubuntu1~18.04.3
    Affected ranges
    • ECOSYSTEM: < 3.0.3-0ubuntu1~18.04.3+esm1

    Update to 3.0.3-0ubuntu1~18.04.3+esm1

  • lxc Ubuntu:Pro:20.04:LTS

    Versions
    • 3.0.4-0ubuntu1
    • 3.0.4-0ubuntu2
    • 1:4.0.0-0ubuntu2
    • 1:4.0.1-0ubuntu1
    • 1:4.0.1-0ubuntu2
    • 1:4.0.2-0ubuntu1
    • 1:4.0.6-0ubuntu1~20.04.1
    • 1:4.0.12-0ubuntu1~20.04.1
    Affected ranges
    • ECOSYSTEM: < 1:4.0.12-0ubuntu1~20.04.1+esm1

    Update to 1:4.0.12-0ubuntu1~20.04.1+esm1

  • lxc Ubuntu:Pro:22.04:LTS

    Versions
    • 1:4.0.10-0ubuntu5
    • 1:4.0.12-0ubuntu1
    • 1:4.0.12-0ubuntu2
    • 1:5.0.0~git2209-g5a7b9ce67-0ubuntu1
    • 1:5.0.0~git2209-g5a7b9ce67-0ubuntu1.1
    Affected ranges
    • ECOSYSTEM: < 1:5.0.0~git2209-g5a7b9ce67-0ubuntu1.1+esm1

    Update to 1:5.0.0~git2209-g5a7b9ce67-0ubuntu1.1+esm1

  • lxc Ubuntu:Pro:24.04:LTS

    Versions
    • 1:5.0.1-0ubuntu7
    • 1:5.0.1-0ubuntu8
    • 1:5.0.3-2ubuntu5
    • 1:5.0.3-2ubuntu7
    • 1:5.0.3-2ubuntu7.1
    • 1:5.0.3-2ubuntu7.2
    • 1:5.0.3-2ubuntu7.3
    Affected ranges
    • ECOSYSTEM: < 1:5.0.3-2ubuntu7.3+esm1

    Update to 1:5.0.3-2ubuntu7.3+esm1

  • lxc Ubuntu:25.10

    Versions
    • 1:6.0.3-1
    • 1:6.0.4-2
    • 1:6.0.4-3
    • 1:6.0.4-4
    • 1:6.0.4-4ubuntu1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • lxc Ubuntu:Pro:26.04:LTS

    Versions
    • 1:6.0.4-4ubuntu1
    • 1:6.0.6-1
    • 1:6.0.6-1ubuntu1
    Affected ranges
    • ECOSYSTEM: < 1:6.0.6-1ubuntu1+esm1

    Update to 1:6.0.6-1ubuntu1+esm1

Original sources

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