CVE-2026-23831 is a medium-severity null pointer dereference vulnerability in github.com/sigstore/rekor (go), affecting versions <= 1.4.3. It is fixed in 1.5.0.
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
The application dereferences a null pointer, causing a crash. Typical impact: denial of service via crash.
CVE-2026-23831 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment.
A fixed version is available (1.5.0). Upgrading removes the vulnerable code path.
go
github.com/sigstore/rekor (<= 1.4.3)github.com/sigstore/rekor → 1.5.0 (go)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter instead of chasing every advisory.
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Already deployed Kodem? See CVE-2026-23831 in your environment →Upgrade github.com/sigstore/rekor to 1.5.0 or later to resolve this vulnerability.
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CVE-2026-23831 is a medium-severity null pointer dereference vulnerability in github.com/sigstore/rekor (go), affecting versions <= 1.4.3. It is fixed in 1.5.0. The application dereferences a null pointer, causing a crash.
CVE-2026-23831 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
github.com/sigstore/rekor (go) versions <= 1.4.3 is affected.
Yes. CVE-2026-23831 is fixed in 1.5.0. Upgrade to this version or later.
Whether CVE-2026-23831 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
Upgrade github.com/sigstore/rekor to 1.5.0 or later.