# RHSA-2026:77610: firefox security update

RHSA-2026:77610, released September 27, 2026, fixes 10 CVEs in firefox (version 140.15.0-1.el10_0). None of them is reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/fix/linux/rhsa-2026-77610
- Platform: Linux
- Released: Sep 27, 2026
- Priority: Urgent (Closes CVE-2026-75874, rated Critical)
- CVEs: 10, exploited: 0, on CISA KEV: 0
- Vendor advisory: https://access.redhat.com/errata/RHSA-2026:77610

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [firefox](https://patchblox.com/security/data/product/linux/firefox.md) | RHEL 10 | 140.15.0-1.el10_0 |

## CVEs this fix closes

| CVE | Priority | Title | CVSS | EPSS | Exploitation |
|---|---|---|---:|---:|---|
| [CVE-2026-75874](https://patchblox.com/security/data/cve/CVE-2026-75874.md) | Urgent | Sandbox escape in the Remote Settings Client component | 10.0 | 0.0046 |  |
| [CVE-2026-84143](https://patchblox.com/security/data/cve/CVE-2026-84143.md) | Urgent | Internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15 | 9.8 | 0.0038 |  |
| [CVE-2026-84119](https://patchblox.com/security/data/cve/CVE-2026-84119.md) | Urgent | Sandbox escape due to use-after-free in the DOM: Navigation component | 9.6 | 0.0032 |  |
| [CVE-2026-84121](https://patchblox.com/security/data/cve/CVE-2026-84121.md) | Urgent | Sandbox escape due to use-after-free in the DOM: Security component | 9.6 | 0.0032 |  |
| [CVE-2026-84145](https://patchblox.com/security/data/cve/CVE-2026-84145.md) | High | Internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15 | 7.5 | 0.0037 |  |
| [CVE-2026-84131](https://patchblox.com/security/data/cve/CVE-2026-84131.md) | High | Privilege escalation due to invalid pointer in the Graphics component | 8.8 | 0.0033 |  |
| [CVE-2026-16365](https://patchblox.com/security/data/cve/CVE-2026-16365.md) | High | Privilege escalation in the DOM: Workers component | 8.8 | 0.0028 |  |
| [CVE-2026-84120](https://patchblox.com/security/data/cve/CVE-2026-84120.md) | High | Use-after-free in the Audio/Video component | 7.5 | 0.0022 |  |
| [CVE-2026-84122](https://patchblox.com/security/data/cve/CVE-2026-84122.md) | High | Use-after-free in the Audio/Video component | 7.5 | 0.0021 |  |
| [CVE-2026-84124](https://patchblox.com/security/data/cve/CVE-2026-84124.md) | High | Use-after-free in the DOM: Core & HTML component | 8.8 | 0.0017 |  |

---

Data as of 2026-11-07T18:46:35Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.