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Mallory
Medium

DoS in Cisco Snort 3 Detection Engine via crafted SSL handshake parsing

IdentifiersCVE-2026-20005CWE-20

Multiple Cisco products are affected by a vulnerability in the Snort 3 Detection Engine where incomplete parsing of ingress SSL/TLS handshake packets can be triggered by an unauthenticated remote attacker. By sending crafted SSL handshake packets, an attacker can cause the Snort 3 Detection Engine to restart unexpectedly, interrupting packet inspection and resulting in a denial-of-service condition for the inspection function.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Unauthenticated remote denial of service against the Snort 3 Detection Engine inspection capability: the engine can be forced to restart, causing interruption of packet inspection (visibility/coverage gap) while the process restarts.

Mitigation

If you can’t patch tonight, do this now.

Limit exposure of the Snort 3 inspection path to untrusted sources where feasible (e.g., reduce/segment traffic that is subject to Snort 3 inspection), and monitor/alert on Snort 3 Detection Engine restarts to detect active exploitation attempts until patches can be applied.

Remediation

Patch, then assume compromise.

Apply Cisco-provided software updates/fixed releases for affected products that include the corrected Snort 3 Detection Engine SSL/TLS handshake parsing logic, per the associated Cisco security advisory for CVE-2026-20005.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
Cisco SystemsSnort 3 Detection Engineapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

What this page doesn’t show

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This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.
Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity1

Community discussion across Reddit, Mastodon, and other social sources.