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

Source: https://junglewise.ai/threats/cve-2026-116585-go-jose-provides-an-implementation-of-the-javascript-object  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-26. Updated: 2026-10-26  
License: CC BY 4.0 with a link back

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)](https://junglewise.ai/threats/technologies/github-com-go-jose-go-jose-v3), [github.com/go-jose/go-jose/v4 (Go)](https://junglewise.ai/threats/technologies/github-com-go-jose-go-jose-v4), [Go-Jose](https://junglewise.ai/threats/technologies/go-jose-go-jose). Vendors: [Go](https://junglewise.ai/threats/vendors/go), [Go-Jose](https://junglewise.ai/threats/vendors/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

  ```sh
  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

- [https://github.com/go-jose/go-jose/commit/35883f7999e87cbd1b1f4cda07fdad8cd71c3dd6](https://github.com/go-jose/go-jose/commit/35883f7999e87cbd1b1f4cda07fdad8cd71c3dd6)
- [https://github.com/go-jose/go-jose/commit/74114c2fa22669a2b2a296746eaa82e15566fd54](https://github.com/go-jose/go-jose/commit/74114c2fa22669a2b2a296746eaa82e15566fd54)

## Related threats

- [Go JOSE RSA parameter validation denial of service](https://junglewise.ai/threats/cve-2026-116587-go-jose-provides-an-implementation-of-the-javascript-object)
- [Go JOSE stack overflow in JSON parsing](https://junglewise.ai/threats/cve-2026-116586-go-jose-provides-an-implementation-of-the-javascript-object)
- [Go JOSE denial of service via panic in JWE decryption](https://junglewise.ai/threats/cve-2026-34986-go-jose-denial-of-service-via-panic-in-jwe-decryption)
- [GO-2025-3485 - DoS in go-jose Parsing in github.com/go-jose/go-jose](https://junglewise.ai/threats/cve-2025-27144-dos-in-go-jose-parsing)
- [GO-2024-2631 - Decompression bomb vulnerability in github.com/go-jose/go-jose](https://junglewise.ai/threats/cve-2024-28180-go-jose-vulnerable-to-improper-handling-of-highly-compressed-data)