CVE-2025-1933 — On 64-bit CPUs, when the JIT compiles WASM i32 return values they can pick up bits from left over memory.

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.

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