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Denial of service in fast-jwt 5.0.0 through 6.2.0 allows authenticated remote attackers with user interaction to cause significant CPU consumption via crafted JWT tokens that trigger catastrophic backtracking in regular expression evaluation when the allowedAud verification option is configured with a regex pattern. The vulnerability exploits attacker-controlled aud claims evaluated against user-supplied regexes, resulting in ReDoS (regular expression denial of service). Vendor-released patch available in version 6.2.1.
fast-jwt before 6.2.1 fails to properly validate JWTs when RegExp modifiers with stateful behavior (/g for global matching and /y for sticky matching) are used in the allowedAud, allowedIss, allowedSub, allowedJti, or allowedNonce options. This causes valid authentication tokens to be rejected in an alternating 50% failure pattern due to RegExp state persistence across verification calls, degrading availability of JWT-protected services without compromising token security itself. The vulnerability is fixed in version 6.2.1.
urql is a GraphQL client that exposes a set of helpers for several frameworks. Rated medium severity (CVSS 6.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Cross-Site Scripting (XSS) vulnerability could allow attackers to inject malicious scripts into web pages viewed by other users.
fast-jwt provides fast JSON Web Token (JWT) implementation. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. Public exploit code available and no vendor patch available.
Denial of service in fast-jwt 5.0.0 through 6.2.0 allows authenticated remote attackers with user interaction to cause significant CPU consumption via crafted JWT tokens that trigger catastrophic backtracking in regular expression evaluation when the allowedAud verification option is configured with a regex pattern. The vulnerability exploits attacker-controlled aud claims evaluated against user-supplied regexes, resulting in ReDoS (regular expression denial of service). Vendor-released patch available in version 6.2.1.
fast-jwt before 6.2.1 fails to properly validate JWTs when RegExp modifiers with stateful behavior (/g for global matching and /y for sticky matching) are used in the allowedAud, allowedIss, allowedSub, allowedJti, or allowedNonce options. This causes valid authentication tokens to be rejected in an alternating 50% failure pattern due to RegExp state persistence across verification calls, degrading availability of JWT-protected services without compromising token security itself. The vulnerability is fixed in version 6.2.1.
urql is a GraphQL client that exposes a set of helpers for several frameworks. Rated medium severity (CVSS 6.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Cross-Site Scripting (XSS) vulnerability could allow attackers to inject malicious scripts into web pages viewed by other users.
fast-jwt provides fast JSON Web Token (JWT) implementation. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. Public exploit code available and no vendor patch available.