# CVE-2026-115683: epiphany: TLS certificate warning bypass via race in tlsErrorPage message handler

Status: published. Published: 2026-10-30. Updated: 2026-11-02.

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.

## Remediation

- workaround: Until a fixed Epiphany build is installed, avoid following links from untrusted sites to HTTPS destinations, and do not rely on Epiphany for sensitive sites when browsing untrusted content. Restrict network access for untrusted browsing where practical (https://cmetaxonomy.org/entries/CME-203.html). Restarting the browser clears any attacker-installed certificate exceptions for the session. (source: CNA: fedora)

## Affected products and versions

- GNOME / Epiphany (epiphany): ≥ 0; < 51.1 (affected, semver). Source: CNA: fedora

## Severity and prioritization

- CVSS 3.1: 6.8 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N; source: CNA: fedora

- CVSS 3.1: 6.8 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N; source: NVD: patrick@puiterwijk.org

- CISA KEV: No listing in collected sources

- EPSS: 0.22% as of 2026-11-01; percentile 12.62%

- SSVC: exploitation poc; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-367

## Exploit evidence

- exploit: https://gitlab.gnome.org/GNOME/epiphany/-/work_items/2978 (ADP: CISA-ADP)

## References

- https://access.redhat.com/security/cve/CVE-2026-115683 (CNA: fedora; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2560012 (CNA: fedora; issue-tracking, x_refsource_REDHAT)

- https://gitlab.gnome.org/GNOME/epiphany/-/work_items/2978 (CNA: fedora)

- https://gitlab.gnome.org/GNOME/epiphany/-/merge_requests/2245 (CNA: fedora)

- https://beford.net/poc/ssl_poc.html (CNA: fedora)

- https://gitlab.gnome.org/GNOME/epiphany/-/work_items/2978 (ADP: CISA-ADP; exploit)

- https://access.redhat.com/security/cve/CVE-2026-115683 (patrick@puiterwijk.org)

- https://beford.net/poc/ssl_poc.html (patrick@puiterwijk.org)

- https://bugzilla.redhat.com/show_bug.cgi?id=2560012 (patrick@puiterwijk.org)

- https://gitlab.gnome.org/GNOME/epiphany/-/merge_requests/2245 (patrick@puiterwijk.org)

- https://gitlab.gnome.org/GNOME/epiphany/-/work_items/2978 (patrick@puiterwijk.org)

- https://gitlab.gnome.org/GNOME/epiphany/-/work_items/2978 (134c704f-9b21-4f2e-91b3-4a467353bcc0)

## Provenance

- CNA: fedora: https://www.cve.org/CVERecord?id=CVE-2026-115683; retrieved 2026-11-02; source updated 2026-11-02

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-115683; retrieved 2026-11-02; source updated 2026-11-02

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-115683; retrieved 2026-11-02; source updated Not reported

Revision: 06f2b62b1fd7df77ed9e17bb70b68e7d9b1cd809de9e99c5a586438d76b6a9dd

Canonical: https://y2.dev/cve/CVE-2026-115683