CVE-2026-74942: Vulnerability in Mozilla Firefox
CVE-2026-74942 is a high-severity privilege escalation vulnerability in the Remote Settings Client component of Mozilla Firefox and Thunderbird. It was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1. The vulnerability allows an unprivileged user to escalate privileges, potentially leading to full compromise of the affected application. Multiple related security advisories from Mozilla confirm the fix and provide additional context on other vulnerabilities addressed in the same releases.
AI Analysis
Technical Summary
CVE-2026-74942 is a privilege escalation vulnerability in the Remote Settings Client component of Mozilla Firefox and Thunderbird. The flaw was reported by Gal Ankonina and is tracked under Bug 2056571. It was addressed in Firefox 154 and corresponding ESR and Thunderbird versions. The vulnerability is part of a set of high-impact security issues fixed in these releases, which include sandbox escapes, use-after-free bugs, mitigation bypasses, and information disclosures. The CVSS v3.1 score is 8.8, indicating high severity with network attack vector, low attack complexity, no privileges required, user interaction required, and high impact on confidentiality, integrity, and availability.
Potential Impact
Successful exploitation of this vulnerability could allow an attacker to escalate privileges within the Firefox or Thunderbird process, potentially leading to execution of arbitrary code with elevated rights. This could compromise user data, browser integrity, and system security. The high CVSS score reflects the critical nature of the impact on confidentiality, integrity, and availability.
Mitigation Recommendations
Mozilla has released official fixes for this vulnerability in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1. Users and administrators should update to these versions or later to remediate the vulnerability. No additional mitigation steps are required beyond applying these official updates.
CVE-2026-74942: Vulnerability in Mozilla Firefox
Description
CVE-2026-74942 is a high-severity privilege escalation vulnerability in the Remote Settings Client component of Mozilla Firefox and Thunderbird. It was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1. The vulnerability allows an unprivileged user to escalate privileges, potentially leading to full compromise of the affected application. Multiple related security advisories from Mozilla confirm the fix and provide additional context on other vulnerabilities addressed in the same releases.
CVSS v3.1
Score 8.8high
Affected software
Mozilla
Firefox
Mozilla
Thunderbird
pkg:github/mozilla/firefoxRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-74942 is a privilege escalation vulnerability in the Remote Settings Client component of Mozilla Firefox and Thunderbird. The flaw was reported by Gal Ankonina and is tracked under Bug 2056571. It was addressed in Firefox 154 and corresponding ESR and Thunderbird versions. The vulnerability is part of a set of high-impact security issues fixed in these releases, which include sandbox escapes, use-after-free bugs, mitigation bypasses, and information disclosures. The CVSS v3.1 score is 8.8, indicating high severity with network attack vector, low attack complexity, no privileges required, user interaction required, and high impact on confidentiality, integrity, and availability.
Potential Impact
Successful exploitation of this vulnerability could allow an attacker to escalate privileges within the Firefox or Thunderbird process, potentially leading to execution of arbitrary code with elevated rights. This could compromise user data, browser integrity, and system security. The high CVSS score reflects the critical nature of the impact on confidentiality, integrity, and availability.
Mitigation Recommendations
Mozilla has released official fixes for this vulnerability in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1. Users and administrators should update to these versions or later to remediate the vulnerability. No additional mitigation steps are required beyond applying these official updates.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mozilla
- Date Reserved
- 2026-08-17T11:57:42.392Z
- State
- PUBLISHED
- Vendor Advisory Urls
- [{"url":"https://www.mozilla.org/security/advisories/mfsa2026-74/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-75/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-76/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-77/","vendor":"Mozilla"}]
Threat ID: 6a845502c6e8be03323673a7
Added to database: 08/18/2026, 12:50:10 UTC
Last enriched: 09/11/2026, 22:03:37 UTC
Last updated: 10/02/2026, 02:46:06 UTC
Views: 38
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