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HighVulnerabilityCVE-2026-116587updated 27 Oct 2026, 19:01 UTC

go-jose: crafted RSA keys in JWKs can make Go apps hang on CPU

If an application reads login keys (JWKs) from outside sources, an attacker can send a specially crafted key that makes the app spend a lot of processor time, slowing down or freezing the service. The attack needs no special setup.

Partial fixOfficial, 2 sources
SeverityHighCVSS 7.5 of 10
Being exploited?UnclearNo reports either way yet
Fix available?Partlygo-jose/v4 4.1.6; go-jose/v3 fixed version not stated in the provided material · since 27 Oct 2026
How sure is this?Official, 2 sourcesBacked by an official source

How the attack works simplified

  1. 1AttackerCrafts a JWS with a malicious RSA key
  2. 2Sent to appRequest carries the JWK in the protected header
  3. 3go-jose parses JWKNo size or consistency bounds checked
  4. 4Validation runscrypto/rsa Validate takes cubic CPU time
  5. 5CPU exhaustedService slows down or stops responding
  6. ResultService denied to legitimate users

What happened

go-jose does not bound the size or consistency of RSA modulus and prime values parsed from JWKs before passing them to crypto/rsa.PrivateKey.Validate, which on Go 1.24+ runs in cubic time, enabling remote denial of service.

Why it is dangerous: Remote attackers can exhaust CPU and cause denial of service in any service that parses untrusted JWKs with go-jose, potentially taking the service offline.

Are you affected?

You are affected if your application uses go-jose v4 at 4.1.5 or earlier, or go-jose v3 at 3.0.5 or earlier, built with Go 1.24 or later, and parses JWKs from untrusted sources.

Package / productAffected versionsFixed in
github.com/go-jose/go-jose/v4 · go<= 4.1.54.1.6
github.com/go-jose/go-jose/v3 · go<= 3.0.5no fix yet

What to do

  1. Update github.com/go-jose/go-jose/v4 to 4.1.6 or later
  2. If you use go-jose v3, check for a fixed v3 release and update to it as soon as available
  3. Until patched, avoid parsing JWKs from untrusted sources

Timeline

  1. 26 Oct 2026, 22:16 UTC
    Publicly disclosed
  2. 26 Oct 2026, 22:16 UTC
    Reported by NVD · NVD
  3. 26 Oct 2026, 22:19 UTC
    Picked up by Zero Radar
  4. 27 Oct 2026, 19:01 UTC
    GitHub Advisory reported on it · GitHub Advisory
  5. 27 Oct 2026, 19:01 UTC
    Fixed version published: github.com/go-jose/go-jose/v4 4.1.6 · GitHub Advisory

Sources 2 reports, oldest first

Official vendor, government CERT or advisory database

Technical details

ID
CVE-2026-116587 · GHSA-mgcc-cww5-fp2q
CVSS
7.5 / 10
EPSS
0.4% chance of exploitation within 30 days
Disclosed
26 Oct 2026, 22:16 UTC
On Zero Radar
26 Oct 2026, 22:19 UTC (3 min after disclosure)
Last change
27 Oct 2026, 19:01 UTC

The plain-language parts and the attack diagram were written by an AI model (anthropic/claude-haiku-5.5) from the sources above. Facts like versions, exploitation and dates come from the sources themselves. How Zero Radar works

go-jose: crafted RSA keys in JWKs can make Go apps hang on CPU · Zero Radar