CVE-2025-1933: Vulnerability in Mozilla Firefox
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.
AI Analysis
Technical Summary
On 64-bit CPUs, the JIT compiler in Mozilla Firefox for WebAssembly (WASM) i32 return values could pick up residual bits from leftover memory, causing the returned values to be misinterpreted as a different type. This memory corruption issue was identified and reported by Tencent Security YUNDING LAB. The vulnerability is tracked as CVE-2025-1933 with a CVSS 3.1 base score of 7.6 (high severity). Mozilla fixed this issue in Firefox 136 and corresponding ESR and Thunderbird versions. The vendor advisories confirm the fix and provide no indication of active exploitation.
Potential Impact
The vulnerability can cause memory corruption by allowing WASM i32 return values to be treated as a different type due to leftover memory bits on 64-bit CPUs. This could lead to unpredictable behavior or crashes and potentially be leveraged for further exploitation. However, no known exploits in the wild have been reported. The impact is rated high based on the CVSS score and potential for memory corruption.
Mitigation Recommendations
Mozilla has released official fixes for this vulnerability in Firefox 136, Firefox ESR 115.21, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8. Users and administrators should update affected products to these versions or later to remediate the issue. Since the vulnerability is patched, no additional mitigation steps are required beyond applying the official updates.
CVE-2025-1933: Vulnerability in Mozilla Firefox
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.
CVSS v3.1
Score 7.6high
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
On 64-bit CPUs, the JIT compiler in Mozilla Firefox for WebAssembly (WASM) i32 return values could pick up residual bits from leftover memory, causing the returned values to be misinterpreted as a different type. This memory corruption issue was identified and reported by Tencent Security YUNDING LAB. The vulnerability is tracked as CVE-2025-1933 with a CVSS 3.1 base score of 7.6 (high severity). Mozilla fixed this issue in Firefox 136 and corresponding ESR and Thunderbird versions. The vendor advisories confirm the fix and provide no indication of active exploitation.
Potential Impact
The vulnerability can cause memory corruption by allowing WASM i32 return values to be treated as a different type due to leftover memory bits on 64-bit CPUs. This could lead to unpredictable behavior or crashes and potentially be leveraged for further exploitation. However, no known exploits in the wild have been reported. The impact is rated high based on the CVSS score and potential for memory corruption.
Mitigation Recommendations
Mozilla has released official fixes for this vulnerability in Firefox 136, Firefox ESR 115.21, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8. Users and administrators should update affected products to these versions or later to remediate the issue. Since the vulnerability is patched, no additional mitigation steps are required beyond applying the official updates.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mozilla
- Date Reserved
- 2025-03-04T12:29:32.686Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Vendor Advisory Urls
- [{"url":"https://www.mozilla.org/security/advisories/mfsa2025-14/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-15/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-16/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-17/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-18/","vendor":"Mozilla"}]
Threat ID: 69091a49c28fd46ded81d048
Added to database: 11/03/2025, 21:10:33 UTC
Last enriched: 06/04/2026, 19:55:43 UTC
Last updated: 09/10/2026, 19:36:49 UTC
Views: 123
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