Improper validation of integrity check value in lua-resty-jwt - #VU163205
Published: November 9, 2026
Vulnerability identifier: #VU163205
CSH Severity: Medium
CVSS v4: 8.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-354
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows an unauthenticated remote attacker to forge encrypted tokens accepted as verified by lua-resty-jwt.
The vulnerability exists due to missing authentication tag length validation when processing JWE tokens using AES-GCM content encryption or key wrapping. An unauthenticated remote attacker with an observed token and correctly guessed plaintext can modify its ciphertext and brute-force a one-byte tag in about 256 attempts on average to produce an accepted forgery.
Affected software
lua-resty-jwt
Remediation
Install security update from vendor's website.
lua-resty-jwt - update to 0.4.0