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    CVE-2026-35039

    fast-jwt provides fast JSON Web Token (JWT) implementation. From 0.0.1 to before 6.2.0, setting up a custom cacheKeyBuilder method which does not properly create unique keys for different tokens can lead to cache collisions. This could cause tokens to be mis-identified during the verification process leading to valid tokens returning claims from different valid tokens and users being mis-identified as other users based on the wrong token. Version 6.2.0 contains a patch.

    Published:Apr 6, 2026
    Last Modified:Apr 22, 2026
    EPS:Apr 6, 2026
    EPSS Score:0.00011
    CVSS Score:9.1

    Affected Products

    Vendor
    Nearform
    Product
    Fast-jwt

    Exploits

    No exploit reference

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-111 JSON Hijacking (aka JavaScript Hijacking)
    CAPEC-141 Cache Poisoning
    CAPEC-142 DNS Cache Poisoning
    CAPEC-148 Content Spoofing
    CAPEC-159 Redirect Access to Libraries
    CAPEC-177 Create files with the same name as files protected with a higher classification
    CAPEC-218 Spoofing of UDDI/ebXML Messages
    CAPEC-384 Application API Message Manipulation via Man-in-the-Middle
    CAPEC-385 Transaction or Event Tampering via Application API Manipulation
    CAPEC-386 Application API Navigation Remapping
    CAPEC-387 Navigation Remapping To Propagate Malicious Content
    CAPEC-388 Application API Button Hijacking
    CAPEC-48 Passing Local Filenames to Functions That Expect a URL
    CAPEC-641 DLL Side-Loading
    CAPEC-665 Exploitation of Thunderbolt Protection Flaws
    CAPEC-701 Browser in the Middle (BiTM)

    Related CVEs

    CVE-2026-44351 (CVSS 9.1) — fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.2.4, a critical authentication-bypass v…
    CVE-2026-35041 (CVSS 4.2) — fast-jwt provides fast JSON Web Token (JWT) implementation. From 5.0.0 to 6.2.0, a denial-of-service condition…
    CVE-2026-35040 (CVSS 5.3) — fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.2.1, using certain modifiers on RegExp …
    CVE-2026-35042 (CVSS 7.5) — fast-jwt provides fast JSON Web Token (JWT) implementation. In 6.1.0 and earlier, fast-jwt does not validate t…
    CVE-2026-34950 (CVSS 9.1) — fast-jwt provides fast JSON Web Token (JWT) implementation. In 6.1.0 and earlier, the publicKeyPemMatcher rege…
    CVE-2025-30144 (CVSS 6.5) — fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 5.0.6, the fast-jwt library does not prop…
    CVE-2023-48223 (CVSS 5.9) — fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to version 3.3.2, the fast-jwt library does …

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High