CVE-2020-26892: Github.com/nats io/jwt Incorrect Handling Of Credential Expiry Vulnerability
CRITICALCVE-2020-26892 is a CRITICAL (CVSS 9.8) incorrect handling of credential expiry vulnerability (CWE-798: Use of Hard-coded Credentials) affecting Github.com/nats io/jwt libraries in the Go ecosystem. The issue involves incorrect handling of credential expiry by /nats-io/nats-server. Remediation is available by upgrading affected packages to version 1.1.0.
CVE-2020-26892 at a Glance
Security Impact
CVSS: 9.8
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
How to Fix CVE-2020-26892
To remediate this vulnerability, upgrade all affected Github.com/nats io/jwt dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
Upgrade github.com/nats-io/jwt to 1.1.0Run the following command in your project directory to verify that all resolved dependencies use the patched release:
inspect dependencies for github.com/nats-io/jwtHow to Check if You Are Affected
To determine whether your application is affected by CVE-2020-26892, inspect your project dependencies for Github.com/nats io/jwt:
inspect dependencies for github.com/nats-io/jwtAnalyze the terminal output to locate any version of Github.com/nats io/jwt in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.1.0), your application is affected.
Note: Verify declared build manifests and deployed runtime container environments.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-798: Use of Hard-coded Credentials, where the product contains hard-coded credentials, such as a password or cryptographic key. In Github.com/nats io/jwt, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2020-26892 Affected Github.com/nats io/jwt Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
github.com/nats-io/jwt
|
Go |
< 1.1.0
|
1.1.0
|
References
Frequently Asked Questions
What is CVE-2020-26892?
Which Github.com/nats io/jwt versions are affected?
What version fixes CVE-2020-26892?
Is github.com/nats-io/jwt affected?
What is the CVSS score of CVE-2020-26892?
What CWE is associated with CVE-2020-26892?
How can I check Go dependencies for CVE-2020-26892?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-4w5x-x539-ppf5",
"modified" : "2025-10-03T19:21:38Z",
"published" : "2022-02-11T23:42:20Z",
"aliases" : [ "CVE-2020-26892" ],
"summary" : "Incorrect handling of credential expiry by /nats-io/nats-server",
"details" : "## Problem Description\n\nNATS nats-server through 2020-10-07 has Incorrect Access Control because of how expired credentials are handled.\n\nThe 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.\n\nA 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.\n\nThe CVE identifier should cover any application using the old JWT API, where the nats-server is one of those applications.\n\n\n## Affected versions\n\n#### JWT library\n\n * all versions prior to 1.1.0\n * fixed after nats-io/jwt PR 103 landed (2020-10-06)\n\n#### NATS Server\n\n * Version 2 prior to 2.1.9\n + 2.0.0 through and including 2.1.8 are vulnerable.\n * fixed with nats-io/nats-server PRs 1632, 1635, 1645\n\n\n## Impact\n\nTime-based credential expiry did not work.\n\n\n## Workaround\n\nHave credentials which only expire after fixes can be deployed.\n\n\n## Solution\n\nUpgrade the JWT dependency in any application using it.\n\nUpgrade the NATS server if using NATS Accounts.",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "Go",
"name" : "github.com/nats-io/jwt"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "1.1.0"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/nats-io/jwt/security/advisories/GHSA-4w5x-x539-ppf5"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-26892"
}, {
"type" : "WEB",
"url" : "https://github.com/nats-io/jwt/commit/e11ce317263cef69619fc1ca743b195d02aa1d8a"
}, {
"type" : "WEB",
"url" : "https://github.com/nats-io/nats-server/commit/1e08b67f08e18cd844dce833a265aaa72500a12f"
}, {
"type" : "WEB",
"url" : "https://advisories.nats.io/CVE/CVE-2020-26892.txt"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/nats-io/jwt"
}, {
"type" : "WEB",
"url" : "https://github.com/nats-io/nats-server/commits/master"
}, {
"type" : "WEB",
"url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/VT67XCLIIBYRT762SVFBYFFTQFVSM3SI"
}, {
"type" : "WEB",
"url" : "https://pkg.go.dev/vuln/GO-2022-0380"
}, {
"type" : "WEB",
"url" : "https://www.openwall.com/lists/oss-security/2020/11/02/2"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-798" ],
"severity" : "CRITICAL",
"github_reviewed" : true,
"github_reviewed_at" : "2021-05-21T21:18:09Z",
"nvd_published_at" : "2020-11-06T08:15:00Z"
}
}