CVE-2026-116585: Go JOSE: Panic during CBC-HMAC processing

Q: Which deployments are exposed to this denial-of-service issue?

Applications are affected if they decrypt attacker-controlled JWE ciphertext using A128CBC-HS256, A192CBC-HS384, or A256CBC-HS512. The issue applies to Go JOSE versions before 4.1.5.

Q: What must an attacker be able to do to trigger the problem?

An attacker needs to supply JWE ciphertext that the application attempts to decrypt with one of the affected CBC-HMAC content-encryption algorithms. An empty ciphertext buffer can reach unpadding and trigger a panic.

Q: How can I determine whether my application is affected?

Review whether the application accepts untrusted JWE input for decryption and whether any of the three affected CBC-HMAC algorithms are enabled or used. Also check whether the Go JOSE version is earlier than 4.1.5.

Q: What remediation is available?

Upgrade Go JOSE to version 4.1.5, which fixes the issue.

Published Oct 26, 2026

Updated

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.

Affected Software

1 affected component

Go JOSE Go JOSE<4.1.5

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade go-jose to a version that resolves this vulnerability.
Fixed in 4.1.5

Event History

Oct 26, 2026

CVE Published

via MITRE·09:06 PM

Data Sourced

via MITRE·09:06 PM

DescriptionWeakness

Frequently Asked Questions

Which deployments are exposed to this denial-of-service issue?

Applications are affected if they decrypt attacker-controlled JWE ciphertext using A128CBC-HS256, A192CBC-HS384, or A256CBC-HS512. The issue applies to Go JOSE versions before 4.1.5.

What must an attacker be able to do to trigger the problem?

An attacker needs to supply JWE ciphertext that the application attempts to decrypt with one of the affected CBC-HMAC content-encryption algorithms. An empty ciphertext buffer can reach unpadding and trigger a panic.

How can I determine whether my application is affected?

Review whether the application accepts untrusted JWE input for decryption and whether any of the three affected CBC-HMAC algorithms are enabled or used. Also check whether the Go JOSE version is earlier than 4.1.5.

What remediation is available?

Upgrade Go JOSE to version 4.1.5, which fixes the issue.

CVE-2026-116585: Go JOSE: Panic during CBC-HMAC processing

Affected Software

Remediation

Event History

Frequently Asked Questions

Which deployments are exposed to this denial-of-service issue?

What must an attacker be able to do to trigger the problem?

How can I determine whether my application is affected?

What remediation is available?

Company

Resources

Contact

Frequently Asked Questions

Which deployments are exposed to this denial-of-service issue?

What must an attacker be able to do to trigger the problem?

How can I determine whether my application is affected?

What remediation is available?