CVE-2025-8027

On 64-bit platforms IonMonkey-JIT only wrote 32 bits of the 64-bit return value space on the stack. Baseline-JIT, however, read the entire 64 bits. This vulnerability affects Firefox < 141, Firefox ESR < 115.26, Firefox ESR < 128.13, Firefox ESR < 140.1, Thunderbird < 141, Thunderbird < 128.13, and Thunderbird < 140.1.

Weakness

The code uses a variable that has not been initialized, leading to unpredictable or unintended results.

Affected Software

Potential Mitigations

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1968423
• https://www.mozilla.org/security/advisories/mfsa2025-56/
• https://www.mozilla.org/security/advisories/mfsa2025-57/
• https://www.mozilla.org/security/advisories/mfsa2025-58/
• https://www.mozilla.org/security/advisories/mfsa2025-59/
• https://www.mozilla.org/security/advisories/mfsa2025-61/
• https://www.mozilla.org/security/advisories/mfsa2025-62/
• https://www.mozilla.org/security/advisories/mfsa2025-63/