CVE-2026-116585: Go JOSE panic on empty JWE ciphertext

CVE-2026-116585 · Severity: medium · CVSS 4 · Published 2026-10-26

Go JOSE is a cryptographic library that implements JSON Web Encryption, Signature, and Token standards for secure data exchange. A flaw in CBC-HMAC content encryption algorithms allows attackers to send specially crafted encrypted messages that trigger a crash, causing denial of service in applications that decrypt untrusted data. Any application using Go JOSE to process JWE tokens from untrusted sources is vulnerable.

Technologies: github.com/go-jose/go-jose/v3 (Go), github.com/go-jose/go-jose/v4 (Go), Go-Jose. Vendors: Go, Go-Jose.

Quick answers

Is CVE-2026-116585 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-116585 being exploited in the wild.
How severe is CVE-2026-116585?
Medium severity, with a CVSS score of 4, published 26 October 2026.
Which products and versions are affected?
github.com/go-jose/go-jose/v3 (Go) <= 3.0.5, SEMVER:introduced=0,last_affected=3.0.5; github.com/go-jose/go-jose/v4 (Go) < 4.1.5, SEMVER:introduced=0,fixed=4.1.5; Go-Jose before 4.1.5.
Is there a fix for CVE-2026-116585?
Yes. github.com/go-jose/go-jose/v4 (Go): upgrade to 4.1.5 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-116585 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-116585?
Check whether you run github.com/go-jose/go-jose/v3 (Go), github.com/go-jose/go-jose/v4 (Go) or Go-Jose at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • github.com/go-jose/go-jose/v4 (Go): upgrade to 4.1.5 or later
    go get github.com/go-jose/go-jose/v4@v4.1.5

Technical details

The vulnerability exists in the CBC-HMAC unpadding function in Go JOSE prior to 4.1.5, where decrypting empty JWE ciphertext with A128CBC-HS256, A192CBC-HS384, or A256CBC-HS512 algorithms results in insufficient validation that causes an out-of-bounds buffer access and panic. An attacker can exploit this by providing untrusted JWE ciphertext that gets decrypted by an application, triggering a denial of service. The fix adds a bounds check to prevent panic on empty ciphertext.

Affected products

  • go-jose Go JOSE before 4.1.5

Identifiers

  • CVE-2026-116585
  • GHSA-4w3g-jfj2-cw2q

Timeline

  • 2026-10-26: disclosed

References

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