What is CVE-2025-2817?

CVE-2025-2817 is a high-severity vulnerability in Mozilla Firefox, classified under Path Traversal. CVSS score: 8.8/10. Published 2025-04-29.

How severe is CVE-2025-2817?

High severity. CVSS v3 base score is 8.8 out of 10.

Is CVE-2025-2817 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Path Traversal in Mozilla Firefox

CVE-2025-2817

Thunderbird's update mechanism allowed a medium-integrity user process to interfere with the SYSTEM-level updater by manipulating the file-locking behavior. By injecting code into the user-privileged process, an attacker could bypass intended access controls, allowing SYSTEM-level file operations on paths controlled by a non-privileged user and enabling privilege escalation. This vulnerability was fixed in Firefox 138, Firefox ESR 128.10, Firefox ESR 115.23, Thunderbird 138, and Thunderbird 128.10.

Vulnerability class: Path Traversal (Directory Traversal)

Published 2025-04-29 · last modified 2026-09-30.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.007 (49.6th percentile), scored 2026-10-04.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 50th percentile — 49.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.006 · newest: 0.007 · change: +0.000

Affected products

Mozilla Firefox — versions 115.23, 128.10, 138
Mozilla Thunderbird — versions 128.10, 138

Weakness classification (CWE)

CWE-22 — Path Traversal

Public proof-of-concept exploits

ARPSyndicate/cve-scores

References

bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
www.mozilla.org/security/advisories/mfsa2025-28/ (Vendor Advisory)
www.mozilla.org/security/advisories/mfsa2025-29/ (Vendor Advisory)
www.mozilla.org/security/advisories/mfsa2025-30/ (Vendor Advisory)
www.mozilla.org/security/advisories/mfsa2025-31/ (Vendor Advisory)
www.mozilla.org/security/advisories/mfsa2025-32/ (Vendor Advisory)
af854a3a-2127-422b-91ae-364da2661108

Frequently asked questions

What is CVE-2025-2817?: CVE-2025-2817 is a high-severity vulnerability in Mozilla Firefox, classified under Path Traversal. CVSS score: 8.8/10. Published 2025-04-29.
How severe is CVE-2025-2817?: High severity. CVSS v3 base score is 8.8 out of 10.
Is CVE-2025-2817 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.