CVE Alert: CVE-2026-126377 – givanz

Vvveb before 1.0.9.0 contains an authentication bypass vulnerability in generateCookie() in system/user/user.php that uses loose comparison to validate MD5 cookie hashes. Unauthenticated attackers can brute-force cookie values until the server’s MD5 computation yields a 0e magic hash, then forge persistent cookies for account takeover.

**Risk verdict:** This is a serious remotely reachable authentication weakness; prioritise exposed deployments, but KEV, SSVC, PoC and EPSS data were not provided, so active exploitation and urgency cannot be confirmed.

**Why this matters:** A successful attack could give an unauthenticated party an administrator-level foothold, enabling access to sensitive content, site defacement or disruption. Persistent account access could also support follow-on attacks against connected services, although no cross-system impact is indicated by the supplied scope assessment.

**Most likely attack path:** The application must be reachable over the network, with no victim interaction or existing account required. Exploitation has high complexity and a stated attack requirement, so it is not necessarily a reliable one-shot attempt; repeated requests or a particular runtime condition may be needed. Scope is unchanged, suggesting impact is confined to the vulnerable application unless an attacker uses the compromised account to reach other systems.

**Who is most exposed:** Organisations running internet-facing instances of this PHP content-management system, especially those hosting valuable sites or administering customer data.

Alert on repeated unauthenticated requests to login or session endpoints.

Review for anomalous persistent sessions or administrator logins from unfamiliar sources.

Check web and application logs for bursts of requests with unusual cookie values.

Mitigation and prioritisation

Upgrade to a vendor-fixed release promptly; validate authentication and session handling after deployment.

Restrict administrative routes to trusted networks or VPNs while patching.

Invalidate existing sessions and rotate administrator credentials if suspicious activity is found.

Apply changes through normal testing and change control; confirm all instances, including forgotten or staging hosts, are covered.

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