Use-after-free in S/MIME decryption during a security device password prompt

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

When Thunderbird asked for a security device password (for example a smartcard PIN or the Primary Password) while decrypting an S/MIME message, the message load could finish or be cancelled while the prompt was open. This freed the message decoder while it was still in use, causing a use-after-free and a potentially exploitable crash. This vulnerability was fixed in Thunderbird 158.0.1 and Thunderbird 153.6.

Source published

20 Oct 2026 19:14:55 UTC

Source modified

27 Oct 2026 18:30:32 UTC

Observed here

27 Oct 2026 19:45:55 UTC

Source terms

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