CVE-2026-23831: Github.com/sigstore/rekor Rekor's COSE V0.0.1 Entry Type Vulnerability

MODERATE
Advisory Identifier: GHSA-273p-m2cw-6833
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CVSS 5.3
CWE-476
Published
Advisory Summary

CVE-2026-23831 is a MODERATE (CVSS 5.3) rekor's cose v0.0.1 entry type vulnerability (CWE-476: NULL Pointer Dereference) affecting Github.com/sigstore/rekor libraries in the Go ecosystem. The issue involves rekor's cose v0.0.1 entry type nil pointer dereference in canonicalize via empty message. Remediation is available by upgrading affected packages to version 1.5.0.

CVE-2026-23831 at a Glance

CVE Identifier CVE-2026-23831
GHSA Identifier GHSA-273p-m2cw-6833
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-476: NULL Pointer Dereference
Affected Product Github.com/sigstore/rekor
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 5.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability Low (A:L)

How to Fix CVE-2026-23831

To remediate this vulnerability, upgrade all affected Github.com/sigstore/rekor dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/sigstore/rekor fixed: 1.5.0 
Upgrade github.com/sigstore/rekor to 1.5.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for github.com/sigstore/rekor

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-23831, inspect your project dependencies for Github.com/sigstore/rekor:

inspect dependencies for github.com/sigstore/rekor

Analyze the terminal output to locate any version of Github.com/sigstore/rekor in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.5.0), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-476: NULL Pointer Dereference, where the product dereferences a pointer that it expects to be valid but is null. In Github.com/sigstore/rekor, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

## 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

CVE-2026-23831 Affected Github.com/sigstore/rekor Versions

1 component(s)
Fixed Versions:
1.5.0
Product / Package Ecosystem Affected Versions Fixed Version
github.com/sigstore/rekor
golang/github.com/sigstore/rekor
Go
< 1.5.0
1.5.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/sigstore/rekor/security/advisories/GHSA-273p-m2cw-6833
NVD — CVE-2026-23831 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-23831
Security Fix Commit FIX COMMIT
https://github.com/sigstore/rekor/commit/39bae3d192bce48ef4ef2cbd1788fb5770fee8cd
Github.com/sigstore/rekor Source Repository REPOSITORY
https://github.com/sigstore/rekor
Github.com/sigstore/rekor Release RELEASE
https://github.com/sigstore/rekor/releases/tag/v1.5.0

Frequently Asked Questions

What is CVE-2026-23831?
CVE-2026-23831 is a security vulnerability in Github.com/sigstore/rekor involving Rekor's COSE v0.0.1 entry type nil pointer dereference in Canonicalize via empty Message under CWE-476: NULL Pointer Dereference.
Which Github.com/sigstore/rekor versions are affected?
Affected versions include releases prior to 1.5.0 across affected packages: github.com/sigstore/rekor.
What version fixes CVE-2026-23831?
Upgrading to 1.5.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/sigstore/rekor affected?
Yes, github.com/sigstore/rekor is affected in releases prior to 1.5.0. Upgrade your dependency to 1.5.0 or later.
What is the CVSS score of CVE-2026-23831?
CVE-2026-23831 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
What CWE is associated with CVE-2026-23831?
CVE-2026-23831 is classified under CWE-476: NULL Pointer Dereference (The product dereferences a pointer that it expects to be valid but is NULL.).
How can I check Go dependencies for CVE-2026-23831?
Run the dependency tree command: 'inspect dependencies for github.com/sigstore/rekor'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-273p-m2cw-6833",
  "modified" : "2026-01-23T15:46:17Z",
  "published" : "2026-01-22T18:41:23Z",
  "aliases" : [ "CVE-2026-23831" ],
  "summary" : "Rekor's COSE v0.0.1 entry type nil pointer dereference in Canonicalize via empty Message",
  "details" : "## Summary\n\nRekor’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`.\n\n## Impact\n\nA 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.\n\n## Patches\n\nUpgrade to v1.5.0\n\n## Workarounds\n\nNone",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/sigstore/rekor"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.5.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.4.3"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/sigstore/rekor/security/advisories/GHSA-273p-m2cw-6833"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-23831"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/sigstore/rekor/commit/39bae3d192bce48ef4ef2cbd1788fb5770fee8cd"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/sigstore/rekor"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/sigstore/rekor/releases/tag/v1.5.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-476" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-22T18:41:23Z",
    "nvd_published_at" : "2026-01-22T22:16:19Z"
  }
}