# DSA-5535-1: firefox-esr security update

DSA-5535-1, released October 25, 2023, fixes 1 CVE in firefox-esr. None of them is reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/fix/linux/dsa-5535-1
- Platform: Linux
- Released: Oct 25, 2023
- Priority: High (Closes CVE-2023-5721, high severity)
- CVEs: 1, exploited: 0, on CISA KEV: 0
- Vendor advisory: https://security-tracker.debian.org/tracker/CVE-2023-5721

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [firefox-esr](https://patchblox.com/security/data/product/linux/firefox-esr.md) | Debian 11.6 (bullseye) | 115.4.0esr-1~deb11u1 |
| [firefox-esr](https://patchblox.com/security/data/product/linux/firefox-esr.md) | Debian 12.15 (bookworm) | 115.4.0esr-1~deb12u1 |

## CVEs this fix closes

| CVE | Priority | Title | CVSS | EPSS | Exploitation |
|---|---|---|---:|---:|---|
| [CVE-2023-5721](https://patchblox.com/security/data/cve/CVE-2023-5721.md) | High | Mozilla Firefox ESR and 5 others: It was possible for certain browser prompts and dialogs to be activated or dismissed unintentionally… | 7.5 | 0.0081 |  |

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Data as of 2026-11-07T06:34:28Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo