Medium severity · published Dec 18, 2025
CVE-2025-40891
HTML injection in in Time Machine functionality in Guardian/CMC before 25.5.0
4.7
CVSS
0.2%
EPSS
No
On KEV
Description
A Stored HTML Injection vulnerability was discovered in the Time Machine Snapshot Diff functionality due to improper validation of network traffic data. An unauthenticated attacker can send specially crafted network packets at two different times to inject HTML tags into asset attributes across two snapshots. Exploitation requires a victim to use the Time Machine Snapshot Diff feature on those specific snapshots and perform specific GUI actions, at which point the injected HTML renders in their browser, enabling phishing and open redirect attacks. Full XSS exploitation is prevented by input validation and Content Security Policy. Attack complexity is high due to multiple required conditions.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
Required
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 7% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CM
CMC · Nozomi Networks
before 25.5.0 · source: vendor, NVD
GU
Guardian · Nozomi Networks
before 25.5.0 · source: vendor, NVD
RA
Affected product
CM
CMC
Nozomi Networks
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