# RLSA-2021:5013: firefox security update

RLSA-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/rlsa-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://errata.rockylinux.org/RLSA-2021:5013

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [firefox](https://patchblox.com/security/data/product/linux/firefox.md) | rocky 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 |  |

---

Data as of 2026-11-08T00:53:09Z 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

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.