CVE-2026-28802 describes a critical vulnerability in Authlib, a Python library for OAuth and OpenID Connect servers, affecting versions 1.6.5 through 1.6.6. This flaw allows attackers to bypass signature verification by submitting a malicious JWT with "alg: none" and an empty signature, leading to unauthorized access or privilege escalation. With a CVSS score of 7.7 (HIGH), the vulnerability is easily exploitable over the network with low attack complexity and no user interaction required, posing a significant risk to confidentiality and integrity. While there is no evidence of active exploitation or public exploit code (Metasploit, Nuclei, ExploitDB), the vulnerability has garnered some community discussion, indicating awareness. Organizations using affected Authlib versions should upgrade to 1.6.7 immediately to mitigate this risk.
| Vendor | Product | Version(s) | CPE |
|---|---|---|---|
>= 1.6.5, < 1.6.7CPE matchmatch criteria | cpe:2.3:a:authlib:authlib:*:*:*:*:*:*:*:* |
CVSS version used by this source: 4.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.
No media coverage found for this CVE.
The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.