CVE-2023-5171

Name: CVE-2023-5171
Creator: NVD / NIST
Published: 2023-09-27T15:19:42.227+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 1.02%

Last modified Jun 17, 2026

CVE-2023-5171 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. During Ion compilation, a Garbage Collection could have resulted in a use-after-free condition, allowing an attacker to write two NUL bytes, and cause a potentially exploitable crash. This vulnerability affects Firefox < 118, Firefox ESR < 115.3, and Thunderbird < 115.3.. EPSS estimates a 1.02% chance of exploitation in the next 30 days.

Description

During Ion compilation, a Garbage Collection could have resulted in a use-after-free condition, allowing an attacker to write two NUL bytes, and cause a potentially exploitable crash. This vulnerability affects Firefox < 118, Firefox ESR < 115.3, and Thunderbird < 115.3.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

EPSS Probability

1.02%

59.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-416

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 118
Mozilla	Firefox Esr	< 115.3
Mozilla	Thunderbird	< 115.3
Debian	Debian Linux	10.0
Debian	Debian Linux	11.0
Debian	Debian Linux	12.0
Fedoraproject	Fedora	39

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1851599Issue Tracking, Permissions Required
https://lists.debian.org/debian-lts-announce/2023/09/msg00034.htmlMailing List, Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/10/msg00015.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/AY642Z6JZODQJE7Z62CFREVUHEGCXGPD/Mailing List, Third Party Advisory
https://www.debian.org/security/2023/dsa-5506Patch, Third Party Advisory
https://www.debian.org/security/2023/dsa-5513Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2023-41/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2023-42/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2023-43/Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1851599Issue Tracking, Permissions Required
https://lists.debian.org/debian-lts-announce/2023/09/msg00034.htmlMailing List, Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/10/msg00015.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/AY642Z6JZODQJE7Z62CFREVUHEGCXGPD/Mailing List, Third Party Advisory
https://www.debian.org/security/2023/dsa-5506Patch, Third Party Advisory
https://www.debian.org/security/2023/dsa-5513Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2023-41/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2023-42/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2023-43/Vendor Advisory

Timeline

Published: Sep 27, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2023-5171?

How severe is CVE-2023-5171?

CVE-2023-5171 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 1.02% probability of exploitation in the next 30 days.

How do I fix CVE-2023-5171?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2023-5171?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST