CVE-2026-84185
MediumCVSS 5.9Summary
In the jwcrypto library, used for implementing JOSE standards, there is a flaw where during verification of a General JSON Serialization JWS with a set of keys, the library fails to correctly identify the specific key ID (kid) and may accept a signature made by any valid key in the set. This can allow an attacker with a valid key to bypass authorization checks in applications that rely on the key ID to identify specific tenants or users.
Risk Assessment
An attacker with a valid key could gain unauthorized access to resources of other users or tenants, potentially leading to confidentiality and integrity breaches.
Recommendation
It is recommended to update jwcrypto to a patched version and review applications for reliance on key ID in authorization processes.
Other vulnerabilities in jwcrypto
See all- CVE-2026-80179Medium
A flaw was found in jwcrypto. A remote attacker can send a specially crafted JSON Web Encryption (JWE) token containing numerous period delimiters. This malformed token can force the JWE.deserialize() function to allocate excessive memory, leading to a MemoryError. This issue results in a denial of service (DoS) for services that process untrusted JWE values.
- CVE-2026-39373Medium
JWCrypto before 1.5.7 does not validate decompressed output size in JWE tokens with ZIP compression. An attacker can send a small token (under 250KB) that decompresses to about 100MB, causing server memory exhaustion.
Original NVD description (English source)
A flaw was found in the jwcrypto library, which is used for implementing Javascript Object Signing and Encryption (JOSE) standards. The issue occurs when the library verifies a General JSON Serialization JWS using a set of keys. Due to a coding error, the library fails to correctly identify the specific key ID (kid) and may instead accept a signature made by any valid key in the set. This can allow an attacker with a valid key to bypass authorization checks in applications that rely on the key ID to identify specific tenants or users.