Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2025-1943 is a high-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Mozilla Firefox. Its CVSS base score is 8.2 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 35th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2025-1943 is a set of memory safety bugs (classified under CWE-122, heap-based buffer overflow) affecting Firefox 135 and Thunderbird 135. These bugs exhibited evidence of memory corruption, which Mozilla presumes could be exploited with sufficient effort to achieve arbitrary code execution. The vulnerability carries a CVSS v3.1 base score of 8.2 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H), highlighting its high severity due to network accessibility and low attack complexity.
Remote attackers can exploit this vulnerability without authentication, privileges, or user interaction, potentially leading to memory corruption and, with advanced techniques, arbitrary code execution on affected systems. The impact primarily targets availability (high) and integrity (low), with no direct confidentiality loss, making it suitable for denial-of-service or code injection scenarios in browser or email client contexts.
Mozilla's security advisories (MFSA 2025-14 and MFSA 2025-17) and associated Bugzilla entries detail the fixes implemented in Firefox 136 and Thunderbird 136. Security practitioners should prioritize updating to these patched versions to mitigate the risks, as no workarounds are specified in the provided references.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-6083
Vulnerability Data
Memory safety bugs present in Firefox 135 and Thunderbird 135. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was…
more
fixed in Firefox 136 and Thunderbird 136.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V1.4.1
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation (including fuzzing and memory-error detectors) can discover heap overflows after they have been coded.
Input validation enforces bounds checking on data written to heap buffers, directly stopping the overflow condition from being introduced.
Security engineering principles require use of memory-safe constructs and bounds-checked allocation routines that avoid introducing heap overflows.
Memory-protection mechanisms limit the ability of a heap overflow to execute attacker-controlled code or corrupt adjacent structures.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure-development practices directly require bounds checking and safe memory handling that prevent heap overflows.
Vulnerability scanning and recording can discover heap-overflow flaws but does not prevent their introduction in code.
Timely patching removes known heap-overflow instances after they exist.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development and acceptance can detect heap overflows before release.
Secure development lifecycle mandates practices that reduce the likelihood of introducing heap overflows.
Application security requirements can specify bounds-checking and safe memory APIs that mitigate heap overflows.
Secure architecture and engineering principles include memory-safety and input-validation controls that address heap overflows.
Secure coding standards directly prescribe techniques (safe functions, bounds checks) that prevent heap-based buffer overflows.