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| Vulnerability ID | VCID-33md-72rd-pydv |
| Aliases |
CVE-2026-44351
GHSA-gmvf-9v4p-v8jc |
| Summary | fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.2.4, a critical authentication-bypass vulnerability in fast-jwt's async key-resolver flow allows any unauthenticated attacker to forge arbitrary JWTs that are accepted as authentic. When the application's key resolver returns an empty string (''), for example via the common keys[decoded.header.kid] || '' JWKS-style fallback, fast-jwt converts it to a zero-length Buffer, hands it to crypto.createSecretKey, derives allowedAlgorithms = ['HS256','HS384','HS512'] from it, and then verifies the token's signature against an empty-key HMAC. The attacker simply computes HMAC-SHA256(key='', input='${header}.${payload}'), which Node accepts without complaint — and the verifier returns the attacker-chosen payload (sub, admin, scopes, etc.) as authentic. This vulnerability is fixed in 6.2.4. |
| Status | Published |
| Exploitability | None |
| Weighted Severity | None |
| Risk | None |
| Affected and Fixed Packages | Package Details |
| System | Score | Found at |
|---|---|---|
| epss | 0.00016 | https://api.first.org/data/v1/epss?cve=CVE-2026-44351 |
| cvssv3.1 | 9.1 | https://github.com/nearform/fast-jwt |
| generic_textual | CRITICAL | https://github.com/nearform/fast-jwt |
| cvssv3.1 | 9.1 | https://github.com/nearform/fast-jwt/security/advisories/GHSA-gmvf-9v4p-v8jc |
| generic_textual | CRITICAL | https://github.com/nearform/fast-jwt/security/advisories/GHSA-gmvf-9v4p-v8jc |
| ssvc | Track | https://github.com/nearform/fast-jwt/security/advisories/GHSA-gmvf-9v4p-v8jc |
| cvssv3.1 | 9.1 | https://nvd.nist.gov/vuln/detail/CVE-2026-44351 |
| generic_textual | CRITICAL | https://nvd.nist.gov/vuln/detail/CVE-2026-44351 |
| Reference id | Reference type | URL |
|---|---|---|
| https://api.first.org/data/v1/epss?cve=CVE-2026-44351 | ||
| https://github.com/nearform/fast-jwt | ||
| https://nvd.nist.gov/vuln/detail/CVE-2026-44351 | ||
| GHSA-gmvf-9v4p-v8jc | https://github.com/advisories/GHSA-gmvf-9v4p-v8jc | |
| GHSA-gmvf-9v4p-v8jc | https://github.com/nearform/fast-jwt/security/advisories/GHSA-gmvf-9v4p-v8jc |
| Attack Vector (AV) | Attack Complexity (AC) | Privileges Required (PR) | User Interaction (UI) | Scope (S) | Confidentiality Impact (C) | Integrity Impact (I) | Availability Impact (A) |
|---|---|---|---|---|---|---|---|
network adjacent_network local physical |
low high |
none low high |
none required |
unchanged changed |
high low none |
high low none |
high low none |
| Attack Vector (AV) | Attack Complexity (AC) | Privileges Required (PR) | User Interaction (UI) | Scope (S) | Confidentiality Impact (C) | Integrity Impact (I) | Availability Impact (A) |
|---|---|---|---|---|---|---|---|
network adjacent_network local physical |
low high |
none low high |
none required |
unchanged changed |
high low none |
high low none |
high low none |
| Attack Vector (AV) | Attack Complexity (AC) | Privileges Required (PR) | User Interaction (UI) | Scope (S) | Confidentiality Impact (C) | Integrity Impact (I) | Availability Impact (A) |
|---|---|---|---|---|---|---|---|
network adjacent_network local physical |
low high |
none low high |
none required |
unchanged changed |
high low none |
high low none |
high low none |
| Percentile | 0.03917 |
| EPSS Score | 0.00016 |
| Published At | June 11, 2026, 12:55 p.m. |
| Date | Actor | Action | Source | VulnerableCode Version |
|---|---|---|---|---|
| 2026-06-11T16:42:38.267120+00:00 | Vulnrichment | Import | https://github.com/cisagov/vulnrichment/blob/develop/2026/44xxx/CVE-2026-44351.json | 38.6.0 |