VulnerabilityPublished 11 Sep 2023Updated 18 Dec 2025

CVE-2023-4573: Mozilla Firefox

Affects Mozilla FirefoxSource CVE Database V5

Not known to be exploited · fixed in 117 : patch Mozilla Firefox soon.

Data as of 26 Oct 2026, 08:30 UTC

Severity

High

Rated High by the CNA (mozilla) · No CVSS score from NVD or the CNA

EPSS: 0.6% chance of exploitation in 30 days – higher than 49% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 117, 115.2, 102.15

Exploitation evidence

Disclosed: evidence found.
CVE published 11 Sep 2023
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Mozilla Firefox to 117, 115.2 or 102.15.

Affected software

Product	Affected	Fixed in
Mozilla Firefox	Affected <117 <102.15 <115.2	Fixed in 117 102.15 115.2

AI-suggested

Mozilla has released official fixes for this vulnerability in Firefox 117, Firefox ESR 102.15, Firefox ESR 115.2, Thunderbird 102.15, and Thunderbird 115.2. Users and administrators should update to these versions or later to remediate the issue. No additional mitigation steps are required beyond applying the official patches.

Description

CVE-2023-4573 is a high-impact memory corruption vulnerability in Mozilla Firefox and Thunderbird involving a use-after-free condition in IPC rendering data handling. This flaw could cause a potentially exploitable crash. It affects Firefox versions prior to 117 and ESR versions prior to 102.15 and 115.2, as well as corresponding Thunderbird versions. Mozilla has released official fixes in Firefox 117, Firefox ESR 102.15, Firefox ESR 115.2, Thunderbird 102.15, and Thunderbird 115.2. The vulnerability is part of a set of memory safety bugs addressed in these releases. No known exploits in the wild have been reported.

Impact

The vulnerability can lead to a use-after-free condition causing a crash that may be exploitable to execute arbitrary code. This represents a high security risk as it could allow attackers to compromise the affected applications. The flaw affects multiple Mozilla products including Firefox and Thunderbird prior to their respective fixed versions. No active exploitation has been reported, but the potential for arbitrary code execution elevates the severity.

Summary

CVE-2023-4573 is a memory corruption vulnerability in Mozilla Firefox and Thunderbird caused by a use-after-free condition when receiving rendering data over IPC. Specifically, the mStream object could be destroyed prematurely during initialization, leading to a potentially exploitable crash. This vulnerability affects Firefox versions earlier than 117, Firefox ESR versions earlier than 102.15 and 115.2, and corresponding Thunderbird versions. Mozilla has fixed this issue in Firefox 117, Firefox ESR 102.15, Firefox ESR 115.2, Thunderbird 102.15, and Thunderbird 115.2. The vulnerability was disclosed publicly on September 11, 2023, and is classified with high impact due to the potential for exploitation. The vendor advisory confirms the fix and does not report any active exploitation in the wild.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 25 Oct 2026, 21:28 UTC

Technical details

References

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