CVE-2026-113869

--- CME Mitigation Guidance (2026-10-20) ---
Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure.

The highest-value action is to prevent premature deallocation of the S/MIME message decoder when message loading completes or is canceled while an interactive password prompt is open: upgrade to Thunderbird 158.0.1 (or the fixed Thunderbird builds), which prevents freeing the message decoder while it remains in use during active S/MIME security device password prompts, closing S/MIME encrypted message delivery triggering an interactive password prompt. Until patched, this is a concern on Thunderbird installations opening S/MIME encrypted messages across all supported platforms, so exercise caution when opening untrusted S/MIME messages and avoid canceling message load operations while smartcard PIN or Primary Password prompt dialogs are displayed. As a compensating measure, maintain Address Space Layout Randomization to randomize Thunderbird process memory and impede gadget predictability, deploy Endpoint Detection and Response agents to detect behavioral anomalies and post-exploitation activity, and enforce Non-Executable Memory (NX/XD bit) protections to block code execution from corrupted heap and data pages. These controls limit blast radius and contain exploitation, but they do not fix the underlying use-after-free defect — apply the upstream patch to fully remediate.

Highest-impact CME: CME-101 ASLR (Address Space Layout Randomization) (medium)