---
id: "CVE-2026-116585"
kind: "vulnerability"
aliases: ["CVE-2026-116585"]
title: "Go JOSE: empty JWE ciphertext causes panic and denial of service"
severity: "medium"
cvss: 6.9
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["go", "jose", "jwe", "jwt", "package"]
not_affected_if: ["no-untrusted-jwe-decryption", "non-cbc-hmac-algorithms"]
published_at: "2026-10-26T22:16:54+00:00"
first_seen_at: "2026-10-26T22:25:33+00:00"
updated_at: "2026-10-26T22:27:56+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-116585", "first_seen_at": "2026-10-26T22:25:33+00:00"}]
---

# Go JOSE: empty JWE ciphertext causes panic and denial of service

Go JOSE is a Go library for JSON Web Encryption, Signature and Token standards. Decrypting untrusted JWE ciphertext with A128CBC-HS256, A192CBC-HS384 or A256CBC-HS512 can pass an empty buffer into unpadding, causing a panic that crashes the process.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `go list -m all | grep jose` and check whether the Go JOSE version is below `4.1.5`.
- Search the code for JWE decryption of input that comes from outside the system, and check which content-encryption algorithm it uses.

## Fix

- Upgrade Go JOSE to `4.1.5` or later.
- Rebuild and redeploy services that decrypt JWE tokens.

## Timeline

- 2026-10-26T22:25:33+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-116585

## From the sources

Go JOSE provides an implementation of the Javascript Object Signing and Encryption set of standards in Go, including support for JSON Web Encryption (JWE), JSON Web Signature (JWS), and JSON Web Token (JWT) standards. Prior to 4.1.5, decrypting untrusted JWE ciphertext with A128CBC-HS256, A192CBC-HS384, or A256CBC-HS512 can pass an empty ciphertext buffer to CBC-HMAC unpadding. Insufficient validation allows the empty buffer to be indexed, causing a panic and denial of service. Applications that decrypt attacker-controlled ciphertext with one of these content-encryption algorithms are affected. This issue is fixed in version 4.1.5.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_