CVE-2026-80179
MediumCVSS 5.9Exploitation Probability (EPSS)
Low risk16th percentile - higher than 16% of all known CVEs
Summary
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.
Risk Assessment
The attack can cause memory exhaustion and service crashes, leading to unavailability of applications using jwcrypto.
Recommendation
It is recommended to update jwcrypto to the latest version that includes a fix to limit memory allocation, and to validate JWE tokens before deserialization.
Other vulnerabilities in jwcrypto
See all- CVE-2026-92091Medium
In the jwcrypto library, the JWK.import_key() function validates the key_ops JWK member for duplicate values using an algorithm with O(n^2) time complexity, and the length of key_ops is not bounded. A remote, unauthenticated attacker can supply a JWK with a large key_ops array to an application that passes attacker-controlled key material to a public key-import API (reachable via ECDH-ES key agreement, OIDC dynamic client registration, DPoP, or ACME account key registration, among others) to consume excessive CPU time, resulting in a denial of service.
- CVE-2026-84185Medium
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.
- 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 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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS