CVE-2026-33204: SimpleJWT has an Unauthenticated Denial of Service via JWE header tampering

March 18, 2026

An unauthenticated attacker can perform a Denial of Service via JWE header tampering when PBES2 algorithms are used. Applications that call JWE::decrypt() on attacker-controlled JWEs using PBES2 algorithms are affected.

References

github.com/advisories/GHSA-xw36-67f8-339x
github.com/kelvinmo/simplejwt
github.com/kelvinmo/simplejwt/security/advisories/GHSA-xw36-67f8-339x
nvd.nist.gov/vuln/detail/CVE-2026-33204

Code Behaviors & Features

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