CVE-2026-34986

Fixed In

4.1.4 and v3.0.5

Workarounds

If the list of keyAlgorithms passed to ParseEncrypted() / ParseEncryptedJSON() / ParseEncryptedCompact() does not include key wrapping algorithms (those ending in KW), your application is unaffected.

If your application uses key wrapping, you can prevalidate to the JWE objects to ensure the encrypted_key field is nonempty. If your application accepts JWE Compact Serialization, apply that validation to the corresponding field of that serialization (the data between the first and second .).

Thanks

Thanks to Datadog's Security team for finding this issue.

Decrypting a JSON Web Encryption (JWE) object will panic if the alg field indicates a key wrapping algorithm (one ending in KW, with the exception of A128GCMKW, A192GCMKW, and A256GCMKW) and the encrypted_key field is empty. The panic happens when cipher.KeyUnwrap() in key_wrap.go attempts to allocate a slice with a zero or negative length based on the length of the encrypted_key.

This code path is reachable from ParseEncrypted() / ParseEncryptedJSON() / ParseEncryptedCompact() followed by Decrypt() on the resulting object. Note that the parse functions take a list of accepted key algorithms. If the accepted key algorithms do not include any key wrapping algorithms, parsing will fail and the application will be unaffected.

This panic is also reachable by calling cipher.KeyUnwrap() directly with any ciphertext parameter less than 16 bytes long, but calling this function directly is less common.

Panics can lead to denial of service.

CVE-2026-34986 has a CVSS score of 7.5 (High). 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 (4.1.4, 3.0.5); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-34986? CVE-2026-34986 is a high-severity security vulnerability in github.com/go-jose/go-jose/v4 (go), affecting versions < 4.1.4. It is fixed in 4.1.4, 3.0.5.
2. How severe is CVE-2026-34986? CVE-2026-34986 has a CVSS score of 7.5 (High). 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.
3. Which packages are affected by CVE-2026-34986?
   • github.com/go-jose/go-jose/v4 (go) (versions < 4.1.4)
   • github.com/go-jose/go-jose/v3 (go) (versions < 3.0.5)
   • github.com/go-jose/go-jose (go) (versions <= 2.6.3)
4. Is there a fix for CVE-2026-34986? Yes. CVE-2026-34986 is fixed in 4.1.4, 3.0.5. Upgrade to this version or later.
5. Is CVE-2026-34986 exploitable, and should I be worried? Whether CVE-2026-34986 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
6. What actually determines whether CVE-2026-34986 is exploitable, and how bad it is? 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.
7. How do I fix CVE-2026-34986?
   • Upgrade github.com/go-jose/go-jose/v4 to 4.1.4 or later
   • Upgrade github.com/go-jose/go-jose/v3 to 3.0.5 or later