CVE•Published 2026-04-07•Modified 2026-06-30•1 article on news•6 live references•NVD data
CVE-2026-5731Mozilla · Firefox
Vulnerability data via NVD (ingested)
CVSS v3.1
9.8
CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS percentile
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Weaknesses (CWE)
Description
Memory safety bugs present in Firefox ESR 115.34.0, Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 149.0.2, Firefox ESR 115.34.1, Firefox ESR 140.9.1, Thunderbird 149.0.2, and Thunderbird 140.9.1.
Timeline
Published 2026-04-07
Modified 2026-06-30
External references
Search for exposed instances
Shodan + Censys queries derived from NVD's CPE data. The vuln tag catches assets Shodan has explicitly linked to this CVE; the product / banner fingerprints find exposed instances even when the vuln tag was never applied (which is common).
Shodan · vuln tag0 hosts
vuln:CVE-2026-5731Hosts Shodan has explicitly fingerprinted as vulnerable.
Shodan · product + version
product:"Mozilla Firefox" version:"115.34.0"Version-pinned fingerprint from NVD's first vulnerable CPE.
Shodan · banner/body mention
http.html:"Firefox"HTTP body or banner mentions "Firefox" — catches deploys Shodan didn't identify as a product.
More intel sources (5)
Shodan report
vuln:CVE-2026-5731Country / ASN / product breakdown for the vuln query.
Censys
vulnerabilities.cve_id: CVE-2026-5731Censys host search filtered to this CVE id.
grep.app
CVE-2026-5731Public source-code mentions — fast PoC discovery.
GitHub code
CVE-2026-5731GitHub code search for direct mentions.
Google dork
"CVE-2026-5731" exploit -site:nvd.nist.govWrite-ups and news, NVD excluded.