CVE-2026-39402

4.3 MEDIUM 0.2% exploit odds Fix listed Auth & access Server

What it is

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.

At a glance

Exploitability: Can be exploited locally on the machine with a low-privilege account. Limited direct impact.
Exploit odds: 0.2% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-05-05 21:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-07-24 21:10 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.2% in the next 30 days (EPSS).
Severity: 4.3 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-05-05 21:16 UTC
Last modified: 2026-07-24 21:10 UTC
Exploit probability: 0.2% · EPSS, next 30 days
Weakness: CWE-863 · Incorrect authorization
Record status: Analyzed

Affected

Linuxcontainers Lxc < 7.0.0

Attack profile CVSS 4.0 · 4.3

Attack vector: Local
Complexity: Low
Attack requirements: Present
Privileges needed: Low
User interaction: None
Confidentiality: None
Integrity: None
Availability: None

Raw vector

CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Is it in your code?

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Fix and advisories

References

NVD record · CVE.org record