# DSA-5509-1: firefox-esr security update

DSA-5509-1, released September 29, 2023, fixes 1 CVE in firefox-esr (version 115.3.1esr-1~deb11u1). One of them is being exploited (CVE-2023-5217); 1 on CISA KEV. Patch Radar priority: Patch now. The product is no longer supported.

- Web page: https://patchblox.com/security/fix/linux/dsa-5509-1
- Platform: Linux
- Released: Sep 29, 2023
- Priority: Patch now (Closes CVE-2023-5217, exploited (CISA KEV))
- CVEs: 1, exploited: 1, on CISA KEV: 1
- Vendor advisory: https://security-tracker.debian.org/tracker/CVE-2023-5217

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [firefox-esr](https://patchblox.com/security/data/product/linux/firefox-esr.md) | Debian 11.6 (bullseye) | 115.3.1esr-1~deb11u1 |

## CVEs this fix closes

| CVE | Priority | Title | CVSS | EPSS | Exploitation |
|---|---|---|---:|---:|---|
| [CVE-2023-5217](https://patchblox.com/security/data/cve/CVE-2023-5217.md) | Patch now | Chromium: CVE-2023-5217 Heap buffer overflow in vp8 encoding in libvpx | 8.8 | 0.4901 | CISA KEV, Disclosed |

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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo