CVE-2025-1009
Published: 04 February 2025
Summary
CVE-2025-1009 is a critical-severity Use After Free (CWE-416) vulnerability in Mozilla Firefox. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Drive-by Compromise (T1189); ranked in the top 25.9% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-2 (Flaw Remediation) and RA-5 (Vulnerability Monitoring and Scanning).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
Directly mandates timely patching of known flaws like CVE-2025-1009 by upgrading to fixed Firefox and Thunderbird versions, comprehensively eliminating the use-after-free vulnerability.
Implements memory protection safeguards such as ASLR and DEP to mitigate exploitation of the use-after-free in XSLT processing, preventing arbitrary code execution despite the flaw.
Enables vulnerability scanning to identify systems with vulnerable Firefox/Thunderbird versions affected by CVE-2025-1009, supporting targeted remediation.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Use-after-free in XSLT processing enables remote arbitrary code execution via malicious webpage (drive-by) or document without auth/UI, directly mapping to client-side exploitation and user execution vectors.
NVD Description
An attacker could have caused a use-after-free via crafted XSLT data, leading to a potentially exploitable crash. This vulnerability was fixed in Firefox 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.
Deeper analysisAI
CVE-2025-1009 is a use-after-free vulnerability (CWE-416) in the processing of crafted XSLT data, which could lead to a potentially exploitable crash. It affects Mozilla Firefox versions prior to 135, Firefox ESR prior to 115.20 and 128.7, Thunderbird prior to 128.7 and 135. The issue carries a CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), indicating critical severity due to its potential for high impact on confidentiality, integrity, and availability.
Any remote attacker can exploit this vulnerability without privileges or user interaction by tricking a target into processing malicious XSLT data, such as via a malicious webpage or document. Successful exploitation could result in arbitrary code execution, data theft, or denial of service, as the use-after-free may allow memory corruption leading beyond a mere crash.
Mozilla's security advisories (MFSA 2025-07 through 2025-10) and Bugzilla entry 1936613 detail the fix, recommending immediate upgrades to Firefox 135, Firefox ESR 115.20 or 128.7, Thunderbird 128.7 or 135. No workarounds are specified beyond applying the patches.
Details
- CWE(s)