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Withdrawn — this advisory has been retracted
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Not in CISA KEV
HIGH severity

Duplicate Advisory: Incorrect Access Control in github.com/nats-io/jwt and github.com/nats-io/nats-server/v2GHSA-9r5x-fjv3-q6h4

HIGHFix: nats-io/jwt#149

GHSA-9r5x-fjv3-q6h4 is a high-severity (CVSS 7.5) CWE-755 vulnerability in github.com/nats-io/jwt/v2. 1 public exploit reference exists, so weaponization risk is real. A fix is available for github.com/nats-io/jwt/v2 — see the affected versions and patch details below.

Also known asBIT-nats-2021-3127CVE-2021-3127GHSA-62mh-w5cv-p88cGHSA-j756-f273-xhp4GO-2022-0386
Published
Updated
Affected
3 pkgs
Patched
3 / 3
Exploits
1 known
Exploitation data as of Oct 12, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs73th percentile — riskier than 73% of all scored CVEsHighest risk
0.00%0.65%1.31%1.96%0.3%1.4%Apr 26Aug 26Oct 26

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

How urgent is this, really

GHSA-9r5x-fjv3-q6h4 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,987 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

3 pkgs affected
🐹github.com/nats-io/jwt/v2🐹github.com/nats-io/nats-server/v2🐹github.com/nats-io/jwt

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

Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-62mh-w5cv-p88c (for github.com/nats-io/jwt) and GHSA-j756-f273-xhp4 (for github.com/nats-io/nats-server). This link is maintained to preserve external references.

Original Description

NATS Server (github.com/nats-io/nats-server/v2/server) 2.x before 2.2.0 and JWT library (github.com/nats-io/jwt/v2) before 2.0.1 have Incorrect Access Control because Import Token bindings are mishandled.

Affected Packages

3 total 3 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/nats-io/jwt/v2all versions2.0.1go get github.com/nats-io/jwt/v2@v2.0.1
🐹Gogithub.com/nats-io/nats-server/v2all versions2.2.0go get github.com/nats-io/nats-server/v2@v2.2.0
🐹Gogithub.com/nats-io/jwtall versions1.2.3-0.20210314221642-a826c77dc9d2go get github.com/nats-io/jwt@v1.2.3-0.20210314221642-a826c77dc9d2

Affected Products

2 products · 2 configurations
Application
nats-serverlinuxfoundation
≥ 2.0.0 && < 2.2.0
range
Application
jwt librarynats
< 2.0.1
range
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

NATS Server 2.x before 2.2.0 and JWT library before 2.0.1 have Incorrect…

advisories.nats.ioNVDMar 2021

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/nats-io/jwt/v2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update github.com/nats-io/jwt/v2 to 2.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9r5x-fjv3-q6h4 is resolved across your whole dependency graph.

  3. Workarounds

    Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

## Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-62mh-w5cv-p88c (for github.com/nats-io/jwt) and GHSA-j756-f273-xhp4 (for github.com/nats-io/nats-server). This link is maintained to preserve external references. ## Original Description NATS Server (github.com/nats-io/nats-server/v2/server) 2.x before 2.2.0 and JWT library (github.com/nats-io/jwt/v2) before 2.0.1 have Incorrect Access Control because Import Token bindings are mishandled.
O3 Security · Impact-Aware SCA

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