Vulnerability in Hayajo Mojolicious::plugin::web::auth::oauth2

CVE-2026-9733

Mojolicious::Plugin::Web::Auth::OAuth2 versions through 0.17 for Perl have an insecure default state parameter. When no state generator is specified in the constructor, the module defaults to using a SHA-1 hash of predictable and low-entropy sources, including the epoch time (which is leaked via the HTTP Date header) and a call to Perl's built-in rand function. A predictable state allows an attacker to hijack another user's session through cross site request forgery (CSRF).

Published · last modified .

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.005 (42.2th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 42nd percentile — 42.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-9733: held from 0.005 to 0.005.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-9733?
CVE-2026-9733 is a critical-severity vulnerability in Hayajo Mojolicious::plugin::web::auth::oauth2, classified under Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG). CVSS score: 9.1/10. Published 2026-06-23.
How severe is CVE-2026-9733?
Critical severity. CVSS v3 base score is 9.1 out of 10.