# RHSA-2021:5013: firefox security update

RHSA-2021:5013, released December 8, 2021, fixes 10 CVEs in firefox (version 0:91.4.0-1.el8_5). None of them is reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/fix/linux/rhsa-2021-5013
- Platform: Linux
- Released: Dec 8, 2021
- Priority: High (Closes CVE-2021-43537, high severity)
- CVEs: 10, exploited: 0, on CISA KEV: 0
- Vendor advisory: https://access.redhat.com/errata/RHSA-2021:5013

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [firefox](https://patchblox.com/security/data/product/linux/firefox.md) | RHEL 8 | 0:91.4.0-1.el8_5 |

## CVEs this fix closes

| CVE | Priority | Title | CVSS | EPSS | Exploitation |
|---|---|---|---:|---:|---|
| [CVE-2021-43537](https://patchblox.com/security/data/cve/CVE-2021-43537.md) | High | Mozilla Firefox ESR and 3 others: An incorrect type conversion of sizes from 64bit to 32bit integers allowed an attacker to corrupt memory… | 9.8 | 0.0217 |  |
| [CVE-2021-43542](https://patchblox.com/security/data/cve/CVE-2021-43542.md) | High | Mozilla Firefox ESR and 3 others: Using XMLHttpRequest, an attacker could have identified installed applications by probing error messages… | 9.8 | 0.0183 |  |
| [CVE-2021-43536](https://patchblox.com/security/data/cve/CVE-2021-43536.md) | High | Mozilla Firefox ESR and 3 others: Under certain circumstances, asynchronous functions could have caused a navigation to fail but expose… | 9.8 | 0.0181 |  |
| [CVE-2021-43539](https://patchblox.com/security/data/cve/CVE-2021-43539.md) | High | Mozilla Firefox ESR and 3 others: Failure to correctly record the location of live pointers across wasm instance calls resulted in a GC… | 9.8 | 0.0173 |  |
| [CVE-2021-43545](https://patchblox.com/security/data/cve/CVE-2021-43545.md) | High | Mozilla Firefox ESR and 3 others: Using the Location API in a loop could have caused severe application hangs and crashes. | 9.8 | 0.0172 |  |
| [CVE-2021-43541](https://patchblox.com/security/data/cve/CVE-2021-43541.md) | High | Mozilla Firefox ESR and 3 others: When invoking protocol handlers for external protocols, a supplied parameter URL containing spaces was… | 9.8 | 0.0169 |  |
| [CVE-2021-43546](https://patchblox.com/security/data/cve/CVE-2021-43546.md) | High | Mozilla Firefox ESR and 3 others: It was possible to recreate previous cursor spoofing attacks against users with a zoomed native cursor. | 9.8 | 0.0151 |  |
| [CVE-2021-43543](https://patchblox.com/security/data/cve/CVE-2021-43543.md) | High | Mozilla Firefox ESR and 3 others: Documents loaded with the CSP sandbox directive could have escaped the sandbox's script restriction by… | 9.8 | 0.0145 |  |
| [CVE-2021-43538](https://patchblox.com/security/data/cve/CVE-2021-43538.md) | High | Mozilla Firefox ESR and 3 others: By misusing a race in our notification code, an attacker could have forcefully hidden the notification… | 9.8 | 0.0125 |  |
| [CVE-2021-4129](https://patchblox.com/security/data/cve/CVE-2021-4129.md) | High | Mozilla Firefox ESR and 3 others: Out-of-bounds Write | 9.8 | 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