CVE-2026-74987: Firefox and Thunderbird internally found memory bugs

critical severity · published 2026-08-18

Internally found bugs in Firefox and Thunderbird. Some of these bugs showed evidence of memory corruption or another security-relevant defect, and the vendor presumes that with enough effort some could have been exploited.

Fixed in: 153.1.0

CVE: CVE-2026-74987

Source: NVD

Am I affected?

You are affected if the installed version is older than 153.1.0. Check the version you have and update to 153.1.0 or later. The fixed version is verified against a vendor or advisory source.

Get the fix

FixLane has a reviewed fix procedure for this incident: a read-only check first, then the fix. Ask the Telegram bot, or connect an AI agent to the FixLane MCP server and call get_fix_prompt with incident id 177 and your operating system.