CVE-2026-107720

7.4 HIGH 0.3% exploit odds Fix listed Other

What it is

fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.3.1, fast-jwt createVerifier accepts an unsigned JWT when key is an empty string or null and algorithms is a non-empty allowlist. Falsy synchronous keys bypass prepareKeyOrSecret, allowedAlgorithms remains active, hasKey is false, and the empty signature avoids the verifySignature gate. An attacker can therefore submit a token containing arbitrary claims without possessing a signing key, resulting in authentication or authorization bypass. Claim validators still run, and non-empty keys, an empty key without algorithms, and the async key resolver path do not have this behavior. This issue is fixed in version 6.3.1.

At a glance

Exploitability: Can be exploited over the network without logging in. High risk of data exposure, data tampering.
Exploit odds: 0.3% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-10-08 17:21 UTC ReservedThe CVE id was reserved by its CNA
2026-10-08 22:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-10-09 15:17 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.3% in the next 30 days (EPSS).
Severity: 7.4 HIGH (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-10-08 22:17 UTC
Last modified: 2026-10-09 15:17 UTC
Exploit probability: 0.3% · EPSS, next 30 days
Weakness: CWE-20 · Improper input validation
Record status: Deferred

Attack profile CVSS 3.1 · 7.4

Attack vector: Network
Complexity: High
Privileges needed: None
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: None

Raw vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Is it in your code?

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Read https://cve-list.com/agent/cve/CVE-2026-107720.md and follow it. Check whether this project is affected by CVE-2026-107720. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record