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Fencer Vulns
high 8.7

CVE-2026-23953 json

Incus container environment configuration newline injection

published 2026-01-22 9 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-3804 , GHSA-x6jc-phwx-hp32 , GO-2026-4359

cvss
8.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

Incus is a system container and virtual machine manager. In versions 6.20.0 and below, a user with the ability to launch a container with a custom YAML configuration (e.g a member of the ‘incus’ group) can create an environment variable containing newlines, which can be used to add additional configuration items in the container’s lxc.conf due to newline injection. This can allow adding arbitrary lifecycle hooks, ultimately resulting in arbitrary command execution on the host. Exploiting this issue on IncusOS requires a slight modification of the payload to change to a different writable directory for the validation step (e.g /tmp). This can be confirmed with a second container with /tmp mounted from the host (A privileged action for validation only). A fix is planned for versions 6.0.6 and 6.21.0, but they have not been released at the time of publication.

Patch / fix

  • go github.com/lxc/incus/v6 6.21.0
  • lxd Debian 13 5.0.2+git20231211.1364ae4-9+deb13u3
  • incus Debian 13 6.0.4-2+deb13u4
  • incus Debian 14 6.0.5-8

debian advisories DEBIAN-CVE-2026-23953

  • govulncheck-vulndb openSUSE Leap 15.6 0.0.20260205T172317-150000.1.146.1

suse advisories SUSE-SU-2026:0403-1

  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1
  • incus openSUSE Tumbleweed 6.22-1.1

opensuse advisories openSUSE-SU-2026:21483-1openSUSE-SU-2026:10280-1

  • incus Alpine 3.24, Alpine 3.23 6.0.5-r6
  • incus-feature Alpine 3.24, Alpine 3.23 6.21.0-r0

alpine advisories ALPINE-CVE-2026-23953

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-23953 updated cvss 8.7

incus: container environment configuration newline injection

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
9 mo ago

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/lxc/incus/security/advisories/GHSA-x6jc-phwx-hp32 referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/user-attachments/files/24473682/environment_newline_injection.sh referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 8.7 CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
GitHub 3.1 8.7 CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

Affected packages

ecosystem package affected fixed in
go github.com/lxc/incus/v6
<6.21.0
>=6.1.0
6.21.0
go github.com/lxc/incus
all versions
 no fix listed

Affected products

  • lxc incus

Classification

Weakness
  • CWE-93 Improper Neutralization of CRLF Sequences

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.