{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata. Fed continuously.","feed_url":"https://feed.craftedsignal.io/products/firefox-esr--140.11/feed.json","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cpes":[],"_cs_cves":[],"_cs_exploited":false,"_cs_has_poc":false,"_cs_poc_references":[],"_cs_products":["Firefox (\u003c 151)","Firefox ESR (\u003c 115.36)","Firefox ESR (\u003c 140.11)"],"_cs_severities":["medium"],"_cs_tags":["firefox","vulnerability","mozilla"],"_cs_type":"advisory","_cs_vendors":["Mozilla"],"content_html":"\u003cp\u003eOn May 19, 2026, Mozilla released security advisories addressing vulnerabilities affecting Firefox and Firefox ESR. The affected products include Firefox versions prior to 151, Firefox ESR versions prior to 115.36, and Firefox ESR versions prior to 140.11. These vulnerabilities could potentially be exploited by attackers to compromise systems running vulnerable versions of Firefox. Users and administrators are urged to review the Mozilla security advisories and apply the necessary updates to mitigate the risk.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAttacker identifies a vulnerable Firefox or Firefox ESR version.\u003c/li\u003e\n\u003cli\u003eAttacker crafts a malicious web page or utilizes an existing compromised website.\u003c/li\u003e\n\u003cli\u003eThe victim visits the malicious web page through the vulnerable Firefox browser.\u003c/li\u003e\n\u003cli\u003eThe malicious web page exploits a vulnerability within Firefox (e.g., memory corruption, use-after-free).\u003c/li\u003e\n\u003cli\u003eSuccessful exploitation allows the attacker to execute arbitrary code on the victim\u0026rsquo;s system.\u003c/li\u003e\n\u003cli\u003eThe attacker gains control of the Firefox process, potentially escalating privileges.\u003c/li\u003e\n\u003cli\u003eThe attacker installs malware, such as a keylogger or remote access trojan (RAT).\u003c/li\u003e\n\u003cli\u003eThe attacker uses the compromised system to steal sensitive data or launch further attacks.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation of these vulnerabilities could allow attackers to execute arbitrary code on a victim\u0026rsquo;s system. This can lead to data theft, malware installation, and further compromise of the affected system. The severity of the impact depends on the specific vulnerability exploited and the privileges gained by the attacker. Given the widespread use of Firefox, a large number of users are potentially at risk if they do not apply the necessary updates.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eUpgrade Firefox to version 151 or later to address the vulnerabilities outlined in MFSA2026-46.\u003c/li\u003e\n\u003cli\u003eUpgrade Firefox ESR to version 115.36 or later to address the vulnerabilities outlined in MFSA2026-47.\u003c/li\u003e\n\u003cli\u003eUpgrade Firefox ESR to version 140.11 or later to address the vulnerabilities outlined in MFSA2026-48.\u003c/li\u003e\n\u003cli\u003eDeploy the Sigma rule \u0026ldquo;Detect Exploitation of Firefox Vulnerabilities via HTTP User-Agent\u0026rdquo; to identify potential exploitation attempts.\u003c/li\u003e\n\u003cli\u003eMonitor web server logs for suspicious User-Agent strings indicative of exploit attempts, as covered by the Sigma rule.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-05-19T19:22:48Z","date_published":"2026-05-19T19:22:48Z","id":"https://feed.craftedsignal.io/briefs/2026-05-mozilla-firefox-vulns/","summary":"Mozilla released security updates on May 19, 2026, addressing vulnerabilities in Firefox versions prior to 151, Firefox ESR versions prior to 115.36, and Firefox ESR versions prior to 140.11.","title":"Mozilla Firefox Security Updates Released","url":"https://feed.craftedsignal.io/briefs/2026-05-mozilla-firefox-vulns/"}],"language":"en","title":"CraftedSignal Threat Feed — Firefox ESR (\u003c 140.11)","version":"https://jsonfeed.org/version/1.1"}