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CRITICAL

Convoy: JWT Signature Verification Bypass Allows Authentication as Arbitrary Users

Published Apr 2, 2026

Description

Convoy is a KVM server management panel for hosting businesses. From version 3.9.0-beta to before version 4.5.1, the JWTService::decode() method did not verify the cryptographic signature of JWT tokens. While the method configured a symmetric HMAC-SHA256 signer via lcobucci/jwt, it only validated time-based claims (exp, nbf, iat) using the StrictValidAt constraint. The SignedWith constraint was not included in the validation step. This means an attacker could forge or tamper with JWT token payloads — such as modifying the user_uuid claim — and the token would be accepted as valid, as long as the time-based claims were satisfied. This directly impacts the SSO authentication flow (LoginController::authorizeToken), allowing an attacker to authenticate as any user by crafting a token with an arbitrary user_uuid. This issue has been patched in version 4.5.1.

Affected products

Remediation

No remediation recorded yet.

References (3)

Change history (0)

No recorded changes yet.

Sources
CVE.org / MITRE
Status PUBLISHED
Assigner GitHub_M
Published Apr 2, 2026
Updated Apr 2, 2026
Reserved Mar 23, 2026
CISA Vulnrichment
Updated Apr 2, 2026
NVD
Status Analyzed
Modified Jul 24, 2026
Red Hat
Severity n/a
Public date n/a
ENISA EUVD
Assigner GitHub_M
Published Apr 2, 2026
Updated Apr 2, 2026
Exploited since n/a
EUVD-2026-18354