CVE-2026-34986 — v4
HIGHCVE-2026-34986 is a high-severity (CVSS 7.5) CWE-248 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 affect by a panic in JWE decryption
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-34986.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-34986 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 379,145 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/go-jose/go-jose/v4🐹github.com/go-jose/go-jose/v3🐹github.com/go-jose/go-joseReal-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
Impact
Decrypting a JSON Web Encryption (JWE) object will panic if the alg field indicates a key wrapping algorithm (one ending in KW, with the exception of A128GCMKW, A192GCMKW, and A256GCMKW) and the encrypted_key field is empty. The panic happens when cipher.KeyUnwrap() in key_wrap.go attempts to allocate a slice with a zero or negative length based on the length of the encrypted_key.
This code path is reachable from ParseEncrypted() / ParseEncryptedJSON() / ParseEncryptedCompact() followed by Decrypt() on the resulting object. Note that the parse functions take a list of accepted key algorithms. If the accepted key algorithms do not include any key wrapping algorithms, parsing will fail and the application will be unaffected.
This panic is also reachable by calling cipher.KeyUnwrap() directly with any ciphertext parameter less than 16 bytes long, but calling this function directly is less common.
Panics can lead to denial of service.
Fixed In
4.1.4 and v3.0.5
Workarounds
If the list of keyAlgorithms passed to ParseEncrypted() / ParseEncryptedJSON() / ParseEncryptedCompact() does not include key wrapping algorithms (those ending in KW), your application is unaffected.
If your application uses key wrapping, you can prevalidate to the JWE objects to ensure the encrypted_key field is nonempty. If your application accepts JWE Compact Serialization, apply that validation to the corresponding field of that serialization (the data between the first and second .).
Thanks
Thanks to Datadog's Security team for finding this issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/go-jose/go-jose/v4 | all versions | 4.1.4go get github.com/go-jose/go-jose/v4@v4.1.4 |
| 🐹Go | github.com/go-jose/go-jose/v3 | all versions | 3.0.5go get github.com/go-jose/go-jose/v3@v3.0.5 |
| 🐹Go | github.com/go-jose/go-jose | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
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 4.1.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34986 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-34986 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-34986. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
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.
This Important impact denial of service vulnerability in the Go JOSE library can be triggered by a crafted JSON Web Encryption (JWE) object specifying a key wrapping algorithm with an empty encrypted_key field, causing a panic and application crash. Applications that parse and decrypt JWE objects from untrusted…
| Product | Fixed in | Advisory |
|---|---|---|
| Cryostat 4 on RHEL 9 | cryostat/cryostat-storage-rhel9:4.2.0-13 | RHSA-2026:17789 |
| Red Hat Enterprise Linux 10 | podman-7:5.8.2-1.el10_2 | RHSA-2026:19017 |
| Red Hat Enterprise Linux 10 | opentelemetry-collector-0:0.144.0-2.el10_2 | RHSA-2026:19135 |
| Red Hat Enterprise Linux 10 | osbuild-composer-0:165.1-2.el10_2 | RHSA-2026:22450 |
| Red Hat Enterprise Linux 10 | image-builder-0:52.1-1.el10_2 | RHSA-2026:22937 |
| Red Hat Enterprise Linux 10 | rh-podman-desktop-0:1.1.2-1.el10_2 | RHSA-2026:57590 |
| Red Hat Enterprise Linux 10.0 Extended Update Support | skopeo-2:1.18.1-3.el10_0.1 | RHSA-2026:16696 |
| Red Hat Enterprise Linux 10.0 Extended Update Support | podman-6:5.4.0-15.el10_0.1 | RHSA-2026:17040 |
Frequently Asked Questions
Is CVE-2026-34986 in your dependencies?
O3 Security finds CVE-2026-34986 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.