9.8
Critical
CVE-2026-74987 Internally found bugs present in Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 153
Description
Internally found bugs present in Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
Affected products and versions
| Product | Affected versions | Fixed in |
|---|---|---|
| Firefox 154 | earliest → < 154 | 154 |
| Firefox 153.1 | earliest → < 153.1 | 153.1 |
| Firefox 140.14 | earliest → < 140.14 | 140.14 |
| Thunderbird 154 | earliest → < 154 | 154 |
| Thunderbird 153.1 | earliest → < 153.1 | 153.1 |
| Thunderbird 140.14 | earliest → < 140.14 | 140.14 |
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