CVE-2026-20011

MEDIUM 5.8

Published 2026-10-21 · Last modified 2026-10-22

Multiple Cisco products are affected by a vulnerability in the Snort 3 SMTP MIME Decoder that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart. This vulnerability is due to a lack of error checking when the MIME fields of the SMTP header are parsed. An attacker could exploit this vulnerability by sending crafted SMTP packets through an established connection to be parsed by Snort 3. A successful exploit could allow the attacker to cause a denial of service (DoS) condition when the Snort 3 Detection Engine unexpectedly restarts.

NO EXPLOITATION SIGNALS

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

Exploitation likelihood

0.5%chance of exploitation in 30 days · 44th percentile

○ In CISA KEV ○ Catalogued PoC

Impact if exploited

5.8CVSS 3.1 · MEDIUM

ConfidentialityNone
IntegrityNone
AvailabilityLow

What an attacker needs

✓Access: Reachable over the network — no local access needed
✓Privileges: No account or privileges required
✓User interaction: No user interaction needed
✓Complexity: No special conditions — reliably repeatable

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept

No public PoC is currently catalogued.

Search for new PoCs

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Tracked sources are checked daily for recent CVEs, including PoCs published after the original disclosure. A later release appears after a tracked source lists it and a refresh succeeds.

Data snapshot: 2026-10-26T13:52:32.101Z