CVE-2026-78426: Logout bypass via alternate JWT spelling
The NeuVector JWT verifier accepts noncanonical Base64URL encodings of the same RSA signature field. An attacker holding a valid JWT that has not expired, but was logged out of NeuVector, can continue using the non-expired token with equivalent spelling of the RSA signature field until the token validity expires.
Affected Software
Event History
Frequently Asked Questions
Who is exposed to this issue?
NeuVector users whose JWTs remain valid after logout are exposed. Exploitation requires an attacker to already possess a valid, unexpired JWT for a NeuVector user.
What must an attacker do to bypass logout?
The attacker must modify the Base64URL spelling of the JWT's RSA signature field to a noncanonical but equivalent encoding. The altered token can be used until the original token's validity expires.
Does this allow use of expired tokens or creation of new valid tokens?
No. The issue applies only to a JWT that was valid and unexpired before logout; the bypass lasts only until that token expires.