Rekor's COSE v0.0.1 entry type nil pointer dereference in Canonicalize via empty Message

Exploitation

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

CVSS

5.3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS

• CVE-2026-23831: 0.43% estimated exploitation activity in the next 30 days; percentile 36.91 (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 Rekor’s cose v0.0.1 entry implementation can panic on attacker-controlled input when canonicalizing a proposed entry with an empty spec.message. validate() returns nil (success) when message is empty, leaving sign1Msg uninitialized, and Canonicalize() later dereferences v.sign1Msg.Payload. Impact A malformed proposed entry of the cose/v0.0.1 type can cause a panic on a thread within the Rekor process. The thread is recovered so the client receives a 500 error message and service still continues, so the availability impact of this is minimal. Patches Upgrade to v1.5.0 Workarounds None

Published by the source

22 Jan 2026, 18:41 UTC

Last modified by the source

23 Jan 2026, 15:46 UTC

Source last checked

26 Oct 2026, 15:14 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-273p-m2cw-6833

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# Patch Next advisory brief: CVE-2026-23831

Advisory: Rekor's COSE v0.0.1 entry type nil pointer dereference in Canonicalize via empty Message
IDs: CVE-2026-23831, GHSA-273p-m2cw-6833
Record: https://patchnext.com/advisories/cve-2026-23831 (revision 1, source checked 26 Oct 2026, 15:14 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 fix available; fixed versions by package: github.com/sigstore/rekor 1.5.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/sigstore/rekor: affected <= 1.4.3; fixed in 1.5.0

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

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/sigstore/rekor.
- 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-273p-m2cw-6833 (GitHub-reviewed advisory GHSA-273p-m2cw-6833 lists affected ranges: Go github.com/sigstore/rekor >=0 <=1.4.3)

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