joserfc: Unbounded JWE General JSON `recipients` Array Leads to CPU Exhaustion (DoS) via Repeated RSA Private-Key Decryption

joserfc · Uncontrolled resource use · CWE-400

Affectedjoserfc

FixNo fix listed yet.

PublishedOct 29, 21:10 · GitHub_M

ScoredOct 29 · 7.5 · GitHub_M

Exploit code publicNone known · checked 21:18 UTC

ExploitedNone known · CISA KEV checked 22:09 UTC

What we know

No known exploitation. CISA KEV, checked 22:09 UTC.

No public exploit code known. Exploit-DB, Metasploit, Nuclei, checked 21:18 UTC.

An attacker only needs network access to the target. No login needed. CVSS: network, no privileges.

A successful attack can take the service down. CVSS impact.

Description

joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.7.5, joserfc.jwe.decrypt_json() accepts a JWE General JSON Serialization recipients array without a count limit and calls decrypt_cek() for every entry. An unauthenticated attacker who can submit a JWE to an endpoint using an RSA key-management algorithm can choose the number of private-key decryption operations performed by one request. The verify_all_recipients option does not reduce this work because the affected loop processes every recipient before consulting that setting, allowing repeated requests to exhaust service CPU without affecting confidentiality or integrity. This issue is fixed in version 1.7.5.

From GitHub_M

Affected and fixed versions

ProductAffectedFixed injoserfc< 1.7.5–

Exploit code

Exploit-DBnone knownMetasploitnone knownNucleinone known

References

github.com/authlib/joserfc/security/advisories/GHSA-jpxq-7h8p-2q76 · github.comrefsource_CONFIRM github.com/authlib/joserfc/commit/d6dc8df6c7609277e741069d3733e43996c1cd17 · github.comrefsource_MISC github.com/authlib/joserfc/releases/tag/1.7.5 · github.comrefsource_MISC

Other CVEs in joserfc

All 8 →

6.9joserfc: Compact JWS size guard allocates attacker-controlled segments before rejection · CVE-2026-119284Oct 29 9.1joserfc: JWS signature verification bypass via empty signatures array in jws.deserialize_json · CVE-2026-102946Oct 15 6.5joserfc claim-validation bypass via array-typed single-string claims (iss/sub/jti) · CVE-2026-75509Aug 24