Loading vulnerability…
CVE-2026-0891 is a Mozilla vulnerability covering multiple memory safety bugs in Firefox, Firefox ESR, Thunderbird, and Thunderbird ESR. Mozilla states that some of the underlying bugs showed evidence of memory corruption and that, with sufficient effort, some could likely be exploited for arbitrary code execution. The issue affects Firefox 146 and earlier versions prior to 147, Firefox ESR 140.6 and earlier versions prior to 140.7, Thunderbird 146 and earlier versions prior to 147, and Thunderbird ESR 140.6 and earlier versions prior to 140.7. Public references indicate the issue aggregates multiple underlying bugs, including Bugzilla entries 1964722, 2000981, 2003100, and 2003278, but the specific vulnerable functions are not identified in the provided content.
Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
If you can’t patch tonight, do this now.
Patch, then assume compromise.
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
12 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
High-severity memory safety bugs identified via fuzzing with corruption indicators and assessed as likely exploitable with effort.
A Mozilla Firefox/Firefox ESR memory-safety vulnerability (memory corruption) that could potentially be exploited for arbitrary code execution.
A Mozilla Firefox vulnerability suspected to be exploited; fixed in Firefox 147 and Firefox ESR 140.7 per the content.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.