Unauthenticated RCE in Cisco AsyncOS Spam Quarantine
CVE-2025-20393 is a critical remote command execution vulnerability in Cisco AsyncOS Software affecting Cisco Secure Email Gateway (SEG) and Cisco Secure Email and Web Manager (SEWM/SMA). Cisco states the flaw is caused by insufficient validation of HTTP requests handled by the Spam Quarantine feature. A remote, unauthenticated attacker can send a crafted HTTP request to a vulnerable appliance and achieve arbitrary command execution on the underlying operating system. Supporting technical analysis in the provided content indicates the vulnerable path is in the End User Quarantine (EUQ) RPC handling used by the Spam Quarantine feature, where a one-byte length field in the protocol can be abused due to improper validation, enabling authentication bypass and unsafe Python pickle deserialization. Successful exploitation results in command execution as root.
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Impact, mitigation & remediation
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Impact
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Exploits
No valid public exploits. Mallory filtered out 10 candidates as fakes, detection scripts, or README-only repos.
All candidate exploits were filtered out by Mallory's validation.
Affected products & vendors
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Recent activity
248 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A specific vulnerability in Cisco Secure Email Gateway that Talos says was exploited in engagements during Q1 2026 as part of vulnerable or exposed infrastructure weaknesses.
A Cisco vulnerability in Email Security Gateway and Secure Email and Web Manager devices that the content states was leveraged by attackers as a zero-day.
Critical vulnerability in Cisco AsyncOS reported as exploited in real-world attacks and attributed to a China-nexus APT actor (no further technical details provided in the content snippet).
Cisco AsyncOS vulnerability exploited as a zero-day by a China-linked APT, enabling RCE (details truncated).
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Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.