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Critical, CVSS 9.1amended

LXD: Update of type field in restricted TLS certificate allows privilege escalation to cluster admin

CVE-2026-34179GHSA-c3h3-89qf-jqm5

What to do

Vendor response not established. Follow the primary source's mitigation guidance and check back for a fix.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • Go github.com/canonical/lxd

    Affected
    >= 0.0.0-20210305023314-538ac3df036e, <= 0.0.0-20260226085519-736f34afb267
    Fixed in
    no fixed version recorded

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
9.1 · CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
EPSS
  • CVE-2026-34179: 0.27% estimated exploitation activity in the next 30 days; percentile 19.81 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary A restricted TLS certificate user can escalate to cluster admin by changing their certificate type from client to server via PUT/PATCH to /1.0/certificates/{fingerprint}. The non-admin guard and reset block in doCertificateUpdate fail to validate or reset the Type field, allowing a caller-supplied value to persist to the database. The modified certificate is matched as a server certificate during TLS authentication, granting ProtocolCluster with full admin privileges. Details doCertificateUpdate in lxd/certificates.go handles PUT/PATCH requests to /1.0/certificates/{fingerprint} for both privileged and unprivileged callers. The access handler is allowAuthenticated, so any trusted TLS user (including restricted) can reach this code. For unprivileged callers (restricted users who fail the EntitlementCanEdit check at line 975), two defenses are intended to prevent field tampering: 1. The guard block validates that Restricted, Name, and Projects match the original database…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-c3h3-89qf-jqm5

  2. Revision 1 · created ·

    Published from osv record GO-2026-5306

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-34179

Advisory: LXD: Update of type field in restricted TLS certificate allows privilege escalation to cluster admin
IDs: CVE-2026-34179, GHSA-c3h3-89qf-jqm5
Record: https://patchnext.com/advisories/cve-2026-34179 (revision 2, source checked 26 Oct 2026, 15:19 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/canonical/lxd: affected >= 0.0.0-20210305023314-538ac3df036e, <= 0.0.0-20260226085519-736f34afb267

## Suggested inspection (read-only)
- Go github.com/canonical/lxd: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/canonical/lxd.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GO-2026-5306 (OSV record GO-2026-5306 lists affected ranges: Go github.com/canonical/lxd >=0)
- Verified: https://github.com/advisories/GHSA-c3h3-89qf-jqm5 (GitHub-reviewed advisory GHSA-c3h3-89qf-jqm5 lists affected ranges: Go github.com/canonical/lxd >=0.0.0-20210305023314-538ac3df036e <=0.0.0-20260226085519-736f34afb267)

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