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CVE-2026-113869

MEDIUM 5.4

Published 2026-10-20 · Last modified 2026-10-20

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.

NO EXPLOITATION SIGNALS

No known exploitation, public exploit, or elevated probability at this time. Track for changes.

Exploitation likelihood

—EPSS not yet scored

○ In CISA KEV ○ Public exploit / PoC

Impact if exploited

5.4CVSS 3.1 · MEDIUM

  • ConfidentialityLow
  • IntegrityNone
  • AvailabilityLow

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ⚠Privileges: Requires a low-privilege account
  • ✓User interaction: No user interaction needed
  • ✓Complexity: No special conditions — reliably repeatable

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept & exploit code

Test against your own equipment

curl -s https://vulnpedia.com/cve/CVE-2026-113869/poc.jsonMachine-readable PoC index for this CVE (for automation).

Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-113869/poc.json

Affected

Vendors Mozilla

Products Thunderbird

Weakness (CWE)

  • CWE-416: Use After Free

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:L

All CVSS metrics

  • MEDIUM 5.4 v3.1 · ADP Primary
    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:L
  • MEDIUM 5.4 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:L

References

Technical & other

Sources: NVD · CVE.org · EPSS