Incus has Unbounded YAML Metadata Decode via Parsing

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

5.3 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-41648: 0.27% estimated exploitation activity in the next 30 days; percentile 19.07 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary User provided image and backup tarballs would be unpacked and YAML files parsed without any size restrictions. This was making it easy for an authenticated user to provide a crafted image or backup tarball that when parsed by Incus would lead to a very large YAML document being loaded into memory, potentially causing the entire server to run out of memory. Details It was found that getImageMetadata and backup.GetInfo call yaml.NewDecoder(tr).Decode() directly on the tar reader without limiting how many bytes the YAML decoder can consume. The tar entry hdr.Size is not checked before decoding. A tar archive can be crafted in which metadata.yaml or backup/index.yaml declares a large size in the tar header, causing the YAML decoder to read and allocate proportional memory on the server. The gopkg.in/yaml.v2 library mitigates YAML alias and anchor bombs, such as “billion laughs,” through its built-in excessive-aliasing check. However, large flat YAML documents with many keys or…

Published by the source

4 May 2026, 19:44 UTC

Last modified by the source

8 May 2026, 21:47 UTC

Source last checked

26 Oct 2026, 15:20 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-67wx-r9xr-x75x

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# Patch Next advisory brief: CVE-2026-41648

Advisory: Incus has Unbounded YAML Metadata Decode via Parsing
IDs: CVE-2026-41648, GHSA-67wx-r9xr-x75x
Record: https://patchnext.com/advisories/cve-2026-41648 (revision 1, source checked 26 Oct 2026, 15:20 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
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/lxc/incus/v6/cmd/incusd: affected <= 6.23.0

## Suggested inspection (read-only)
- Go github.com/lxc/incus/v6/cmd/incusd: 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/lxc/incus/v6/cmd/incusd.
- 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://github.com/advisories/GHSA-67wx-r9xr-x75x (GitHub-reviewed advisory GHSA-67wx-r9xr-x75x lists affected ranges: Go github.com/lxc/incus/v6/cmd/incusd >=0 <=6.23.0)

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