Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2026-44351— fast-jwt: Empty HMAC secret accepted via async key resolver - JWT auth bypass

Quick assessment

Affected
nearform fast-jwt
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

fast-jwt是Nearform开源的一个 JSON Web Token 实现。 fast-jwt 6.2.4之前版本存在授权问题漏洞，该漏洞源于异步密钥解析流程中的关键身份验证绕过漏洞，允许未经身份验证的攻击者伪造任意JWT令牌。

CVSS 9.1 · Critical EPSS 0.33% · P25

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
nearform fast-jwt < 6.2.4 affected
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-44351

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
fast-jwt: Empty HMAC secret accepted via async key resolver - JWT auth bypass
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
认证机制不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
fast-jwt 授权问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
fast-jwt是Nearform开源的一个 JSON Web Token 实现。 fast-jwt 6.2.4之前版本存在授权问题漏洞，该漏洞源于异步密钥解析流程中的关键身份验证绕过漏洞，允许未经身份验证的攻击者伪造任意JWT令牌。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
nearform fast-jwt < 6.2.4 -

II. Public POCs for CVE-2026-44351

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-44351

请登录查看更多情报信息。

Vendor Advisories for CVE-2026-44351 (1)

IV. Related Vulnerabilities

Same product: fast-jwt
Same vendor: nearform
Same weakness: CWE-287

V. Comments for CVE-2026-44351

No comments yet

Leave a comment