# RHSA-2026:26539: thunderbird security update

RHSA-2026:26539, released May 19, 2026, fixes 22 CVEs in thunderbird (version 140.11.0-1.el10_0). None of them is reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/fix/linux/rhsa-2026-26539
- Platform: Linux
- Released: May 19, 2026
- Priority: High (Closes CVE-2026-8956, high severity)
- CVEs: 22, exploited: 0, on CISA KEV: 0
- Vendor advisory: https://access.redhat.com/errata/RHSA-2026:26539

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [thunderbird](https://patchblox.com/security/data/product/linux/thunderbird.md) | RHEL 10 | 140.11.0-1.el10_0 |

## CVEs this fix closes

| CVE | Priority | Title | CVSS | EPSS | Exploitation |
|---|---|---|---:|---:|---|
| [CVE-2026-8956](https://patchblox.com/security/data/cve/CVE-2026-8956.md) | High | Integer overflow in the Networking: JAR component | 9.8 | 0.0061 |  |
| [CVE-2026-8946](https://patchblox.com/security/data/cve/CVE-2026-8946.md) | High | Incorrect boundary conditions in the Audio/Video: Web Codecs component | 7.5 | 0.0056 |  |
| [CVE-2026-8953](https://patchblox.com/security/data/cve/CVE-2026-8953.md) | High | Sandbox escape due to use-after-free in the Disability Access APIs component | 9.6 | 0.0053 |  |
| [CVE-2026-8975](https://patchblox.com/security/data/cve/CVE-2026-8975.md) | High | Memory safety bugs fixed in Thunderbird 140.11 and Thunderbird 151 | 8.8 | 0.0047 |  |
| [CVE-2026-8094](https://patchblox.com/security/data/cve/CVE-2026-8094.md) | High | Other issue in the WebRTC component | 9.8 | 0.0045 |  |
| [CVE-2026-8954](https://patchblox.com/security/data/cve/CVE-2026-8954.md) | High | Incorrect boundary conditions, integer overflow in the Audio/Video component | 7.5 | 0.0043 |  |
| [CVE-2026-8959](https://patchblox.com/security/data/cve/CVE-2026-8959.md) | High | Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component | 9.6 | 0.0042 |  |
| [CVE-2026-8092](https://patchblox.com/security/data/cve/CVE-2026-8092.md) | High | Memory safety bugs fixed in Thunderbird ESR 140.10.2 and Thunderbird 150.0.2 | 8.1 | 0.0041 |  |
| [CVE-2026-8947](https://patchblox.com/security/data/cve/CVE-2026-8947.md) | High | Use-after-free in the DOM: Bindings (WebIDL) component | 7.5 | 0.0041 |  |
| [CVE-2026-8968](https://patchblox.com/security/data/cve/CVE-2026-8968.md) | High | Denial-of-service due to invalid pointer in the Audio/Video: Web Codecs component | 7.5 | 0.0041 |  |
| [CVE-2026-8955](https://patchblox.com/security/data/cve/CVE-2026-8955.md) | High | Privilege escalation in the DOM: Workers component | 8.8 | 0.0039 |  |
| [CVE-2026-8957](https://patchblox.com/security/data/cve/CVE-2026-8957.md) | High | Privilege escalation in the Enterprise Policies component | 8.8 | 0.0039 |  |
| [CVE-2026-8962](https://patchblox.com/security/data/cve/CVE-2026-8962.md) | High | Mitigation bypass in the DOM: Security component | 8.1 | 0.0037 |  |
| [CVE-2026-8974](https://patchblox.com/security/data/cve/CVE-2026-8974.md) | High | Memory safety bugs fixed in Thunderbird 140.11 and Thunderbird 151 | 8.8 | 0.0037 |  |
| [CVE-2026-8958](https://patchblox.com/security/data/cve/CVE-2026-8958.md) | High | Information disclosure, sandbox escape in the Security: Process Sandboxing component | 8.6 | 0.0034 |  |
| [CVE-2026-8961](https://patchblox.com/security/data/cve/CVE-2026-8961.md) | High | Spoofing issue in the Form Autofill component | 7.5 | 0.0032 |  |
| [CVE-2026-8090](https://patchblox.com/security/data/cve/CVE-2026-8090.md) | High | Use-after-free in the DOM: Networking component | 7.5 | 0.0032 |  |
| [CVE-2026-8401](https://patchblox.com/security/data/cve/CVE-2026-8401.md) | High | Sandbox escape in the Profile Backup component | 9.8 | 0.0031 |  |
| [CVE-2026-8970](https://patchblox.com/security/data/cve/CVE-2026-8970.md) | High | Privilege escalation in the Security component | 8.8 | 0.0031 |  |
| [CVE-2026-8391](https://patchblox.com/security/data/cve/CVE-2026-8391.md) | High | Other issue in the JavaScript Engine component | 7.5 | 0.0030 |  |
| [CVE-2026-8388](https://patchblox.com/security/data/cve/CVE-2026-8388.md) | High | Incorrect boundary conditions in the JavaScript Engine: JIT component | 7.5 | 0.0024 |  |
| [CVE-2026-8950](https://patchblox.com/security/data/cve/CVE-2026-8950.md) | High | Same-origin policy bypass in the Networking: HTTP component | 9.3 | 0.0019 |  |

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Data as of 2026-11-07T12:40:37Z 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