# RHSA-2026:77631: thunderbird security update

RHSA-2026:77631, released September 30, 2026, fixes 13 CVEs in thunderbird (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-2026-77631
- Platform: Linux
- Released: Sep 30, 2026
- Priority: Urgent (Closes CVE-2026-75874, rated Critical)
- CVEs: 13, exploited: 0, on CISA KEV: 0
- Vendor advisory: https://access.redhat.com/errata/RHSA-2026:77631

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [thunderbird](https://patchblox.com/security/data/product/linux/thunderbird.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-2026-84639](https://patchblox.com/security/data/cve/CVE-2026-84639.md) | Urgent | Uninitialized memory in MIME parsing | 9.1 | 0.0032 |  |
| [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-2026-84641](https://patchblox.com/security/data/cve/CVE-2026-84641.md) | High | Information disclosure due to malicious IMAP server response | 7.5 | 0.0027 |  |
| [CVE-2026-84640](https://patchblox.com/security/data/cve/CVE-2026-84640.md) | High | One byte overflow read in mail parser | 7.5 | 0.0026 |  |
| [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 |  |

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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

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