CVE-2026-9733

Critical

Published: 23 June 2026

Published

23 June 2026

Modified

23 June 2026

KEV Added

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Patch

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CVSS Score v3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS Score 0.0034 25.8th percentile

Risk Priority 70 floored blend · peak EPSS

Summary

CVE-2026-9733 is a critical-severity PRNG (CWE-338) vulnerability. Its CVSS base score is 9.1 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Browser Session Hijacking (T1185); ranked at the 25.8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

OWASP Top 10 for Web (2025)

EU & UK References

🇪🇺 ENISA EUVD: EUVD-2026-38421

Vulnerability details

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).

CWE(s): CWE-338 CWE-340

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1185 Browser Session Hijacking Collection

Adversaries may take advantage of security vulnerabilities and inherent functionality in browser software to change content, modify user-behaviors, and intercept information as part of various browser session hijacking techniques.

attack.mitre.org →

Why these techniques?

Predictable OAuth state enables CSRF-based session hijacking as described.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0