# RHSA-2021:0288: firefox security update

RHSA-2021:0288, released January 27, 2021, fixes 5 CVEs in firefox (version 0:78.7.0-2.el8_3). None of them is reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/fix/linux/rhsa-2021-0288
- Platform: Linux
- Released: Jan 27, 2021
- Priority: High (Closes CVE-2021-23964, high severity)
- CVEs: 5, exploited: 0, on CISA KEV: 0
- Vendor advisory: https://access.redhat.com/errata/RHSA-2021:0288

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [firefox](https://patchblox.com/security/data/product/linux/firefox.md) | RHEL 8 | 0:78.7.0-2.el8_3 |

## CVEs this fix closes

| CVE | Priority | Title | CVSS | EPSS | Exploitation |
|---|---|---|---:|---:|---|
| [CVE-2021-23964](https://patchblox.com/security/data/cve/CVE-2021-23964.md) | High | Firefox ESR and 2 others: Mozilla developers reported memory safety bugs present in Firefox 84 and Firefox ESR 78.6. | 8.8 | 0.0136 |  |
| [CVE-2021-23960](https://patchblox.com/security/data/cve/CVE-2021-23960.md) | High | Firefox ESR and 2 others: Performing garbage collection on re-declared JavaScript variables resulted in a user-after-poison, and… | 8.8 | 0.0129 |  |
| [CVE-2021-23954](https://patchblox.com/security/data/cve/CVE-2021-23954.md) | High | Firefox ESR and 2 others: Using the new logical assignment operators in a JavaScript switch statement could have caused a type… | 8.8 | 0.0119 |  |
| [CVE-2020-26976](https://patchblox.com/security/data/cve/CVE-2020-26976.md) | Routine | Firefox ESR and 1 other: When a HTTPS pages was embedded in a HTTP page, and there was a service worker registered for the former,… | 6.5 | 0.0164 |  |
| [CVE-2021-23953](https://patchblox.com/security/data/cve/CVE-2021-23953.md) | Routine | Firefox ESR and 2 others: If a user clicked into a specifically crafted PDF, the PDF reader could be confused into leaking cross-origin… | 4.3 | 0.0106 |  |

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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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo