CVE-2025-1933
CVE-2025-1933 is a high-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 7.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.
Key facts
- Severity: High (CVSS 3.x base score 7.6)
- EPSS exploit prediction: 0% (21st percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2025-7438
- Affected product: Mozilla Firefox
- Published:
- Last modified:
Description
On 64-bit CPUs, when the JIT compiles WASM i32 return values they can pick up bits from left over memory. This can potentially cause them to be treated as a different type. This vulnerability was fixed in Firefox 136, Firefox ESR 115.21, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8.
Frequently asked questions
- What is CVE-2025-1933?
- On 64-bit CPUs, when the JIT compiles WASM i32 return values they can pick up bits from left over memory. This can potentially cause them to be treated as a different type. This vulnerability was fixed in Firefox 136, Firefox ESR 115.21, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8.
- How severe is CVE-2025-1933?
- CVE-2025-1933 has a CVSS 3.x base score of 7.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability high.
- Is CVE-2025-1933 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (21st percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2025-1933?
- CVE-2025-1933 primarily affects Mozilla Firefox. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
- How do I fix CVE-2025-1933?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2025-1933 have an EU (EUVD) identifier?
- Yes. CVE-2025-1933 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-7438.
- When was CVE-2025-1933 published?
- CVE-2025-1933 was published on 2025-03-04 and last updated on 2026-06-17.
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1946004
- https://www.mozilla.org/security/advisories/mfsa2025-14/
- https://www.mozilla.org/security/advisories/mfsa2025-15/
- https://www.mozilla.org/security/advisories/mfsa2025-16/
- https://www.mozilla.org/security/advisories/mfsa2025-17/
- https://www.mozilla.org/security/advisories/mfsa2025-18/
- https://lists.debian.org/debian-lts-announce/2025/03/msg00006.html
Affected products (3)
- cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
- cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
- cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
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