Use-after-free in Mozilla Networking: HTTP component
CVE-2026-12291 is a use-after-free vulnerability in Mozilla's Networking: HTTP component affecting Firefox, Firefox ESR, and Thunderbird prior to the fixed releases. The flaw is described by Mozilla as a use-after-free condition that can lead to memory corruption. While the specific vulnerable function is not provided in the available content, the bug resides in HTTP networking code and is triggerable in the context of processing attacker-controlled web content or network interactions handled by the browser/mail client. As a memory safety flaw, successful exploitation could corrupt process memory and potentially be developed into code execution.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
If you can’t patch tonight, do this now.
Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
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.
Recent activity
7 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
The version that knows your environment.
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.