How severe is CVE-2026-116585?

No CVSS score has been assigned to CVE-2026-116585 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-116585?

CVE-2026-116585 affects the following packages: github.com/go-jose/go-jose/v4 (Go), github.com/go-jose/go-jose/v3 (Go). Ecosystems affected: Go.

How do I fix CVE-2026-116585?

Update github.com/go-jose/go-jose/v4 to 4.1.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-116585 is resolved across your whole dependency graph.

How do I detect CVE-2026-116585 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/go-jose/go-jose/v4, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-116585 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2026-116585 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-116585 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-116585?

CVE-2026-116585 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 18th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-116585?

CVE-2026-116585 is classified as CWE-129 (CWE-129). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-116585 published, and has it been updated?

CVE-2026-116585 was published on October 26, 2026 and was last updated on October 29, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹 Go

Not in CISA KEV

CVE-2026-116585 — go-jose

Fix: go-jose/go-jose@35883f7

CVE-2026-116585 is a CWE-129 vulnerability in github.com/go-jose/go-jose/v4. A fix is available for github.com/go-jose/go-jose/v4 — see the affected versions and patch details below.

Go JOSE: Panic during CBC-HMAC processing

Also known asGHSA-4w3g-jfj2-cw2q

Published

Oct 26, 2026

Updated

Oct 29, 2026

Affected

2 pkgs

Patched

1 / 2

Exploits

None indexed

Exploitation data as of Oct 28, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs18th percentile — riskier than 18% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

2 pkgs affected

🐹github.com/go-jose/go-jose/v4🐹github.com/go-jose/go-jose/v3

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Summary

Decrypting a ciphertext with "A128CBC-HS256", "A192CBC-HS384", or "A256CBC-HS512" can result in a panic on untrusted input.

Note this advisory is the same as https://github.com/go-jose/go-jose/security/advisories/GHSA-6mp9-8xrw-74r4.

Details

Insufficient validation of parameters can lead to attempting to index into an empty buffer. See https://github.com/go-jose/go-jose/pull/292.

Workarounds

If the application does not require the CBC-HMAC modes for content encryption, and is using github.com/go-jose/go-jose/v4, do not include them in the list of ContentEncryption algorithms passed to ParseEncrypted / ParseEncryptedJSON / ParseEncryptedCompact.

Impact

Denial of service vulnerability. Any application which decrypts untrusted ciphertexts with the indicated algorithms is affected.

Acknowledgements

Thanks to Joshua Rogers of AISLE Research for reporting this problem.

Affected Packages

2 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/go-jose/go-jose/v4`	all versions	4.1.5`go get github.com/go-jose/go-jose/v4@v4.1.5`
🐹Go	`github.com/go-jose/go-jose/v3`	all versions	No fix

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/go-jose/go-jose/v4, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/go-jose/go-jose/v4 to 4.1.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-116585 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant

This vulnerability is rated as an Important severity flaw because an unauthenticated remote attacker can cause an immediate denial of service by triggering an unhandled panic without requiring special privileges. Within Red Hat OpenShift and hybrid cloud environments, various core management and authentication proxy…

Workaround published by Red Hat

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

Source: Red Hat security advisory for CVE-2026-116585 (CC BY 4.0)

Frequently Asked Questions

### Summary Decrypting a ciphertext with "A128CBC-HS256", "A192CBC-HS384", or "A256CBC-HS512" can result in a panic on untrusted input. Note this advisory is the same as https://github.com/go-jose/go-jose/security/advisories/GHSA-6mp9-8xrw-74r4. ### Details Insufficient validation of parameters can lead to attempting to index into an empty buffer. See https://github.com/go-jose/go-jose/pull/292. ### Workarounds If the application does not require the CBC-HMAC modes for content encryption, and is using github.com/go-jose/go-jose/v4, do not include them in the list of ContentEncryption alg

O3 Security · Impact-Aware SCA

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