Severity by source
AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Attacker needs no target privileges since the signing key is public (PR:N) but must achieve mirror control/MITM (AC:H) and the victim must run a root package install (UI:R), yielding full root RCE.
Primary rating from Vendor (github).
CVSS VectorVendor: github
Lifecycle Timeline
6DescriptionCVE.org
lxc-ci contains continuous integration and image-build scripts for LXC. Prior to the 2026-05-28 Arch Linux image publication, images built from images/archlinux.yaml retain the same pacman local-signing private key in /etc/pacman.d/gnupg and redistribute it to every container or virtual machine created from that image. An attacker who controls an HTTP package mirror or can intercept mirror traffic can use the shared pacman signing private key to sign modified packages that affected clients accept as trusted. Installing those packages permits arbitrary code execution as root on the client system. This issue is fixed in Arch Linux images published on or after 2026-05-28.
AnalysisAI
Hard-coded pacman signing key in lxc-ci's Arch Linux image build lets a mirror-position attacker forge trusted packages and execute code as root on affected guests. Images built from images/archlinux.yaml and published before 2026-05-28 embed the same pacman local-signing private key in /etc/pacman.d/gnupg, and every container or VM created from those images inherits it (CWE-321); because the key can be recovered from any published image, the assessed vector (AV:N/AC:H/PR:N/UI:R) positions an unauthenticated remote attacker who operates or intercepts an HTTP package mirror to sign tampered packages that clients accept during a root install or update. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires three concrete conditions: (1) the victim system was created from an lxc-ci Arch Linux image built from images/archlinux.yaml BEFORE 2026-05-28, so it still contains the shared local-signing private key in /etc/pacman.d/gnupg; (2) the attacker occupies a mirror-serving or on-path position - either operating/compromising an HTTP package mirror the client uses, or intercepting mirror traffic (the key itself is not secret, as it can be recovered from any published image); and (3) the victim performs a package install/update operation as root (e.g., pacman -Syu) that fetches the attacker-signed package. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | This is a genuine supply-chain/cryptographic-trust failure, not a paper-high-CVSS issue, but its real-world risk is gated by attacker network position rather than by the raw 7.2 score. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Apply the vendor-released fix by using Arch Linux images published on or after 2026-05-28 and, for affected systems, recreating the container or VM from a fixed image instead of patching in place - the old private key was already exposed, so any package locally signed with it must be considered untrusted, and import of the upstream commit 082cb34ea19791a0424feafd9da67b94881ea40a is the source-level fix per advisory https://github.com/lxc/lxc-ci/security/advisories/GHSA-4h59-f67g-5qxp. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory all running containers/VMs and base images for lxc-ci Arch Linux images built from images/archlinux.yaml and published before 2026-05-28; inspect /etc/pacman.d/gnupg for embedded private keys; freeze deployment of affected images; block new root package installs/updates on affected guests until remediated; restrict pacman to trusted HTTPS mirrors; and review recent package operations for signs of tampering. …
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External POC / Exploit Code
Leaving vuln.today
EUVD-2026-82369