# RHSA-2021:1353: thunderbird security update

RHSA-2021:1353, released April 26, 2021, fixes 9 CVEs in thunderbird (version 0:78.10.0-1.el8_3). None of them is reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/fix/linux/rhsa-2021-1353
- Platform: Linux
- Released: Apr 26, 2021
- Priority: High (Closes CVE-2021-23994, high severity)
- CVEs: 9, exploited: 0, on CISA KEV: 0
- Vendor advisory: https://access.redhat.com/errata/RHSA-2021:1353

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [thunderbird](https://patchblox.com/security/data/product/linux/thunderbird.md) | RHEL 8 | 0:78.10.0-1.el8_3 |

## CVEs this fix closes

| CVE | Priority | Title | CVSS | EPSS | Exploitation |
|---|---|---|---:|---:|---|
| [CVE-2021-23994](https://patchblox.com/security/data/cve/CVE-2021-23994.md) | High | Firefox ESR and 2 others: A WebGL framebuffer was not initialized early enough, resulting in memory corruption and an out of bound… | 8.8 | 0.0176 |  |
| [CVE-2021-23961](https://patchblox.com/security/data/cve/CVE-2021-23961.md) | High | Firefox ESR and 1 other: Further techniques that built on the slipstream research combined with a malicious webpage could have… | 7.4 | 0.0148 |  |
| [CVE-2021-23999](https://patchblox.com/security/data/cve/CVE-2021-23999.md) | High | Firefox ESR and 2 others: If a Blob URL was loaded through some unusual user interaction, it could have been loaded by the System… | 8.8 | 0.0137 |  |
| [CVE-2021-29946](https://patchblox.com/security/data/cve/CVE-2021-29946.md) | High | Firefox ESR and 2 others: Ports that were written as an integer overflow above the bounds of a 16-bit integer could have bypassed… | 8.8 | 0.0130 |  |
| [CVE-2021-23995](https://patchblox.com/security/data/cve/CVE-2021-23995.md) | High | Firefox ESR and 2 others: When Responsive Design Mode was enabled, it used references to objects that were previously freed. | 8.8 | 0.0118 |  |
| [CVE-2021-24002](https://patchblox.com/security/data/cve/CVE-2021-24002.md) | High | Firefox ESR and 2 others: When a user clicked on an FTP URL containing encoded newline characters (%0A and %0D), the newlines would… | 8.8 | 0.0113 |  |
| [CVE-2021-29945](https://patchblox.com/security/data/cve/CVE-2021-29945.md) | Routine | Firefox ESR and 2 others: The WebAssembly JIT could miscalculate the size of a return type, which could lead to a null read and… | 6.5 | 0.0120 |  |
| [CVE-2021-23998](https://patchblox.com/security/data/cve/CVE-2021-23998.md) | Routine | Firefox ESR and 2 others: Through complicated navigations with new windows, an HTTP page could have inherited a secure lock icon… | 6.5 | 0.0059 |  |
| [CVE-2021-29948](https://patchblox.com/security/data/cve/CVE-2021-29948.md) | Routine | Thunderbird: Signatures are written to disk before and read during verification, which might be subject to a race… | 2.5 | 0.0029 |  |

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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