What is CVE-2025-49710?

CVE-2025-49710 is a critical-severity vulnerability in Mozilla Firefox, classified under Integer Overflow or Wraparound. CVSS score: 9.8/10. Published 2025-06-11.

How severe is CVE-2025-49710?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Integer overflow in Mozilla Firefox

CVE-2025-49710

An integer overflow was present in `OrderedHashTable` used by the JavaScript engine. This vulnerability was fixed in Firefox 139.0.4.

Vulnerability class: Integer Overflow

Published 2025-06-11 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.007 (52.9th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 53rd percentile — 52.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: +0.001

Affected products

Mozilla Firefox — versions 139.0.4

Weakness classification (CWE)

CWE-190 — Integer Overflow or Wraparound

References

bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
www.mozilla.org/security/advisories/mfsa2025-47/ (Vendor Advisory)

Frequently asked questions

What is CVE-2025-49710?: CVE-2025-49710 is a critical-severity vulnerability in Mozilla Firefox, classified under Integer Overflow or Wraparound. CVSS score: 9.8/10. Published 2025-06-11.
How severe is CVE-2025-49710?: Critical severity. CVSS v3 base score is 9.8 out of 10.