What is GHSA-2c64-vj8g-vwrq?

(This advisory is canonically https://advisories.nats.io/CVE/CVE-2020-26892.txt ) ## Problem Description NATS nats-server through 2020-10-07 has Incorrect Access Control because of how expired credentials are handled. The NATS accounts system has expiration timestamps on credentials; the library had an API which encouraged misuse and an `IsRevoked()` method which misused its own API. A new `IsClaimRevoked()` method has correct handling and the nats-server has been updated to use this. The old `IsRevoked()` method now always returns true and other client co

How severe is GHSA-2c64-vj8g-vwrq?

No CVSS score has been assigned to GHSA-2c64-vj8g-vwrq yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-2c64-vj8g-vwrq?

GHSA-2c64-vj8g-vwrq affects the following packages: github.com/nats-io/nats-server/v2 (Go). Ecosystems affected: Go.

How do I fix GHSA-2c64-vj8g-vwrq?

Update github.com/nats-io/nats-server/v2 to 2.1.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2c64-vj8g-vwrq is resolved across your whole dependency graph.

How do I detect GHSA-2c64-vj8g-vwrq in my Go dependencies?

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

How do I mitigate GHSA-2c64-vj8g-vwrq if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is GHSA-2c64-vj8g-vwrq actively exploited in the wild?

No public exploit code has been indexed for GHSA-2c64-vj8g-vwrq 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 GHSA-2c64-vj8g-vwrq?

GHSA-2c64-vj8g-vwrq has an EPSS (Exploit Prediction Scoring System) score of 2.1%, placing it in the 81th 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 GHSA-2c64-vj8g-vwrq?

GHSA-2c64-vj8g-vwrq is classified as Hard-coded Credentials (CWE-798). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-2c64-vj8g-vwrq published, and has it been updated?

GHSA-2c64-vj8g-vwrq was published on May 21, 2021 and was last updated on September 10, 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

Incorrect handling of credential expiry by /nats-io/nats-serverGHSA-2c64-vj8g-vwrq

Fix: nats-io/jwt@e11ce31

GHSA-2c64-vj8g-vwrq is a Hard-coded Credentials vulnerability in github.com/nats-io/nats-server/v2. A fix is available for github.com/nats-io/nats-server/v2 — see the affected versions and patch details below.

Also known asCVE-2020-26892 GHSA-4w5x-x539-ppf5GO-2022-0380

Published

May 21, 2021

Updated

Sep 10, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

2.1%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs81th percentile — riskier than 81% of all scored CVEsHighest risk

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

Real-World Exposure

1 pkg affected

🐹github.com/nats-io/nats-server/v2

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

(This advisory is canonically https://advisories.nats.io/CVE/CVE-2020-26892.txt )

Problem Description

NATS nats-server through 2020-10-07 has Incorrect Access Control because of how expired credentials are handled.

The NATS accounts system has expiration timestamps on credentials; the https://github.com/nats-io/jwt library had an API which encouraged misuse and an IsRevoked() method which misused its own API.

A new IsClaimRevoked() method has correct handling and the nats-server has been updated to use this. The old IsRevoked() method now always returns true and other client code will have to be updated to avoid calling it.

The CVE identifier should cover any application using the old JWT API, where the nats-server is one of those applications.

Affected versions

JWT library

all versions prior to 1.1.0
fixed after nats-io/jwt PR 103 landed (2020-10-06)

NATS Server

Version 2 prior to 2.1.9
- 2.0.0 through and including 2.1.8 are vulnerable.
fixed with nats-io/nats-server PRs 1632, 1635, 1645

Impact

Time-based credential expiry did not work.

Workaround

Have credentials which only expire after fixes can be deployed.

Solution

Upgrade the JWT dependency in any application using it.

Upgrade the NATS server if using NATS Accounts.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/nats-io/nats-server/v2`	all versions	2.1.9`go get github.com/nats-io/nats-server/v2@v2.1.9`

Affected Products

2 products · 2 configurations

fedorafedoraproject

1 version

Application

nats-serverlinuxfoundation

< 2.1.9

range

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/nats-io/nats-server/v2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/nats-io/nats-server/v2 to 2.1.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2c64-vj8g-vwrq is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

(This advisory is canonically https://advisories.nats.io/CVE/CVE-2020-26892.txt ) ## Problem Description NATS nats-server through 2020-10-07 has Incorrect Access Control because of how expired credentials are handled. The NATS accounts system has expiration timestamps on credentials; the <https://github.com/nats-io/jwt> library had an API which encouraged misuse and an `IsRevoked()` method which misused its own API. A new `IsClaimRevoked()` method has correct handling and the nats-server has been updated to use this. The old `IsRevoked()` method now always returns true and other client co

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