CVE-2026-107721
MEDIUMDescription
fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.3.0, fast-jwt createVerifier accepts Infinity for clockTolerance because its option validation checks type and negativity but not finiteness. In validateClaimDateValue, infinite positive and negative modifiers make exp and nbf comparisons always pass, allowing expired or not-yet-active tokens to be accepted. The verifier cache also derives infinite bounds, so entries created under this configuration can remain valid until eviction. Exploitation requires an application administrator or equivalent configuration path to set clockTolerance to Infinity. This issue is fixed in version 6.3.0.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 25% of all known CVEs.
References
Related Vulnerabilities
Other CWE-613 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2014-2595 | Critical | 9.8 | 17% | - | - |
| CVE-2023-30403 | High | 7.5 | 14% | - | - |
| CVE-2020-27422 | Critical | 9.8 | 7.9% | - | - |
| CVE-2014-3616 | Medium | 4.3 | 5.7% | - | Fix |
| CVE-2021-3144 | Critical | 9.1 | 5.2% | - | Fix |
| CVE-2021-24019 | High | 8.1 | 3.9% | - | Fix |
Common questions
How do I fix CVE-2026-107721?
Upgrade fast-jwt to 6.3.0 or later.
Is CVE-2026-107721 being actively exploited?
Not that we know of. CVE-2026-107721 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.33% is the estimated probability that it will be exploited in the next 30 days. That is higher than 25% of all scored CVEs.
How severe is CVE-2026-107721?
CVE-2026-107721 has a CVSS v3 base score of 5.9, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-107721 affect?
Published advisories record a fix for fast-jwt (npm). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-10-09.