CVE-2025-3839
📋 TL;DR
Epiphany browser's external URL handler feature can be abused to exploit vulnerabilities in external applications, making them appear remotely exploitable. The browser fails to properly warn users before opening these handlers, potentially leading to code execution on client devices. This affects users of Epiphany browser on systems with vulnerable external URL handlers.
💻 Affected Systems
- Epiphany (GNOME Web browser)
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution on client device by exploiting vulnerabilities in external URL handlers through malicious websites.
Likely Case
Exploitation of known vulnerabilities in external applications via crafted web pages, leading to application compromise.
If Mitigated
Limited impact if external handlers are patched and browser warnings are implemented.
🎯 Exploit Status
Exploitation depends on vulnerabilities in external URL handlers; browser itself enables the attack vector.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check vendor advisory for specific version
Vendor Advisory: https://access.redhat.com/security/cve/CVE-2025-3839
Restart Required: Yes
Instructions:
1. Check vendor advisory for patched version. 2. Update Epiphany browser via package manager. 3. Restart browser after update.
🔧 Temporary Workarounds
Disable external URL handlers
linuxConfigure browser to block or prompt for all external URL handler requests.
gsettings set org.gnome.epiphany enable-external-url-handlers false
Use alternative browser
allTemporarily switch to a different browser without this vulnerability.
🧯 If You Can't Patch
- Implement network filtering to block malicious websites
- Educate users to avoid clicking unknown links and update external applications
🔍 How to Verify
Check if Vulnerable:
Check Epiphany version and compare with patched version in vendor advisory.Check Version:
epiphany --versionVerify Fix Applied:
Confirm Epiphany version matches or exceeds patched version from advisory.📡 Detection & Monitoring
Log Indicators:
- Browser logs showing external URL handler activations from unknown sources
Network Indicators:
- HTTP requests to known malicious domains triggering handler calls
SIEM Query:
source="epiphany" AND event="external-url-handler" AND dest_app NOT IN (approved_handlers)