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Mallory
Medium

SSH key-based authentication bypass in Cisco Secure Firewall ASA proprietary SSH stack

IdentifiersCVE-2026-20009CWE-287

A vulnerability in Cisco Secure Firewall Adaptive Security Appliance (ASA) Software’s proprietary SSH implementation when using SSH key-based authentication allows an unauthenticated remote attacker to authenticate as a specific user without possessing that user’s private key. The issue is caused by insufficient validation of user-supplied input during the SSH authentication phase; by sending crafted authentication input, an attacker can complete login as the targeted user provided they know a valid username and have the corresponding public key. Successful exploitation permits command execution as that specific user (not root).

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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 login to the ASA over SSH as a specific user, enabling execution of commands with that user’s privileges. The advisory notes exploitation does not grant root access.

Mitigation

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

Information currently not available in the provided content.

Remediation

Patch, then assume compromise.

Information currently not available in the provided content (no fixed versions or patch guidance included).
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 SystemsAdaptive Security Appliance Softwareoperating_system

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

What this page doesn’t show

The version that knows your environment.

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

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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.