What is CVE-2023-29540?

CVE-2023-29540 is a medium-severity vulnerability in Mozilla Firefox, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 6.1/10. Published 2023-06-02.

How severe is CVE-2023-29540?

Medium severity. CVSS v3 base score is 6.1 out of 10.

Open Redirect in Mozilla Firefox

CVE-2023-29540

Using a redirect embedded into <code>sourceMappingUrls</code> could allow for navigation to external protocol links in sandboxed iframes without <code>allow-top-navigation-to-custom-protocols</code>. This vulnerability affects Firefox for Android < 112, Firefox < 112, and Focus for Android < 112.

Vulnerability class: Open Redirect

Published 2023-06-02 · last modified 2026-08-19.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (22.0th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 22nd percentile — 22.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

Mozilla Firefox — versions unspecified
Mozilla Firefox For Android — versions unspecified
Mozilla Firefox Mobile
Mozilla Focus
Mozilla Focus For Android — versions unspecified

Weakness classification (CWE)

CWE-601 — URL Redirection to Untrusted Site (Open Redirect)

References

www.mozilla.org/security/advisories/mfsa2023-13/ (Vendor Advisory)
bugzilla.mozilla.org/show_bug.cgi (Permissions Required, Issue Tracking, Vendor Advisory)

Frequently asked questions

What is CVE-2023-29540?: CVE-2023-29540 is a medium-severity vulnerability in Mozilla Firefox, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 6.1/10. Published 2023-06-02.
How severe is CVE-2023-29540?: Medium severity. CVSS v3 base score is 6.1 out of 10.