China-Linked Hackers Exploiting Zero-Day in Cisco Security Gear
Source SecurityWeek
Exploited in the wild · KEV due 24 Dec 2025 : apply the vendor's fix or mitigations to Cisco Secure Email now.
Data as of 26 Oct 2026, 11:07 UTC
- KEV deadline
- US federal agencies must patch by this date; a sensible deadline for everyone else.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:HExploitation evidence
t = 0 is the CVE’s publication on cve.org
Disclosed: evidence found.
CVE published 17 Dec 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: evidence found.
Listed in CISA KEV the same day as disclosure
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
Timeline
CVE ID reserved
by Cisco Systems, Inc.
, 1.2 years before disclosure
CVE published
on cve.org
, t = 0
In Threat Radar
record ingested
, 14 minutes after disclosure
Added to CISA KEV (opens in a new tab)
exploitation confirmed
, the same day as disclosure
KEV remediation due
US federal deadline
, 7 days after disclosure
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA KEV (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| CiscoCisco Secure Email | Affected
| Fixed in– |
| CiscoCisco Secure Email and Web Manager | Affected
| Fixed in– |
Ciscocisco/cisco-secure-emailpkg:rpm/cisco/cisco-secure-emailOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Until official patches are released, European organizations should implement several specific mitigations: 1) Isolate affected Cisco appliances on segmented network zones with strict access controls to limit lateral movement. 2) Employ enhanced monitoring and logging on these devices to detect anomalous activities indicative of exploitation attempts. 3) Restrict administrative access to the appliances using multi-factor authentication and limit it to trusted personnel only. 4) Deploy network intrusion detection/prevention systems with updated signatures to identify exploit attempts targeting this vulnerability. 5) Conduct thorough audits of appliance configurations and firmware versions to identify potential exposure. 6) Engage with Cisco’s security advisories and apply patches immediately upon release. 7) Educate security teams on indicators of compromise related to this threat and prepare incident response plans tailored to attacks on security infrastructure. 8) Consider temporary compensating controls such as disabling non-essential services or features on the affected appliances to reduce attack surface.
Description
The critical zero-day is tracked as CVE-2025-20393 and it impacts Secure Email Gateway and Secure Email and Web Manager appliances. The post China-Linked Hackers Exploiting Zero-Day in Cisco Security Gear appeared first on SecurityWeek .