What is CVE-2023-5728?

CVE-2023-5728 is a high-severity vulnerability in Mozilla Firefox, classified under Use After Free. CVSS score: 7.5/10. Published 2023-10-25.

How severe is CVE-2023-5728?

High severity. CVSS v3 base score is 7.5 out of 10.

Is CVE-2023-5728 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Use After Free in Mozilla Firefox

CVE-2023-5728

During garbage collection extra operations were performed on a object that should not be. This could have led to a potentially exploitable crash. This vulnerability affects Firefox < 119, Firefox ESR < 115.4, and Thunderbird < 115.4.1.

Vulnerability class: Use-After-Free

Published 2023-10-25 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.012 (66.7th percentile), scored 2026-10-05.

Low probability of exploitation in the next 30 days, but still tracked. 67th percentile — 66.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.012 · newest: 0.012 · change: 0.000

Affected products

Mozilla Firefox — versions unspecified
Mozilla Firefox Esr — versions unspecified
Mozilla Firefox Esr
Mozilla Thunderbird — versions unspecified
Debian Linux — versions 10.0, 11.0

Weakness classification (CWE)

CWE-416 — Use After Free

Public proof-of-concept exploits

fkie-cad/nvd-json-data-feeds

References

bugzilla.mozilla.org/show_bug.cgi (Issue Tracking, Vendor Advisory)
www.mozilla.org/security/advisories/mfsa2023-45/ (Vendor Advisory)
www.mozilla.org/security/advisories/mfsa2023-46/ (Vendor Advisory)
www.mozilla.org/security/advisories/mfsa2023-47/ (Vendor Advisory)
www.debian.org/security/2023/dsa-5535 (Mailing List, Third Party Advisory)
lists.debian.org/debian-lts-announce/2023/10/msg00037.html (Mailing List, Third Party Advisory)
www.debian.org/security/2023/dsa-5538 (Third Party Advisory)
lists.debian.org/debian-lts-announce/2023/10/msg00042.html (Mailing List, Third Party Advisory)

Frequently asked questions

What is CVE-2023-5728?: CVE-2023-5728 is a high-severity vulnerability in Mozilla Firefox, classified under Use After Free. CVSS score: 7.5/10. Published 2023-10-25.
How severe is CVE-2023-5728?: High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2023-5728 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.