GNOME Epiphany TLS/SSL Certificate Warning Page race condition

Summaryinfo

A vulnerability has been found in GNOME Epiphany and classified as critical. This issue affects some unknown processing of the component TLS/SSL Certificate Warning Page. This manipulation causes race condition. This vulnerability appears as CVE-2026-115683. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability classified as critical was found in GNOME Epiphany (the affected version unknown). Affected by this vulnerability is an unknown part of the component TLS/SSL Certificate Warning Page. The manipulation with an unknown input leads to a race condition vulnerability. The CWE definition for the vulnerability is CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

A race condition in Epiphany allows a malicious website to bypass the TLS/SSL certificate warning page. Epiphany registers the main-world script message handler "tlsErrorPage" so its internal TLS error page can implement "Accept Risk and Proceed". The handler was registered immediately before loading the error page, leaving a brief window where the previously loaded untrusted origin could still call window.webkit.messageHandlers.tlsErrorPage.postMessage(...). The only authorization check compares a numeric WebKit page id that increments predictably; an attacker can burst-guess ids and approve a certificate exception with no user click. If a victim visits malicious site A that redirects to site B with an invalid certificate, site A can, for a few milliseconds, disable TLS certificate error warnings for host B until Epiphany is restarted, enabling man-in-the-middle or site spoofing for that host. Upstream report: https://gitlab.gnome.org/GNOME/epiphany/-/work_items/2978 Proof of concept: https://beford.net/poc/ssl_poc.html Fix: https://gitlab.gnome.org/GNOME/epiphany/-/merge_requests/2245 (register handlers on LOAD_COMMITTED). No fixed release tagged yet; reporter and maintainer describe all current versions as affected. Maintainer notes the risky registration timing dates to commit 1da1caed (Epiphany 45.x era); before that the handlers were always registered and similarly reachable from web content.

It is possible to read the advisory at access.redhat.com. This vulnerability is known as CVE-2026-115683 since 10/23/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Vendor

• GNOME

Name

• Epiphany

License

• open-source

Website

• Vendor: https://www.gnome.org/

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