Security readout for executives and security teams
Plain-English summary
Nozomi Networks Guardian and CMC contain a flaw in the Credentials Manager that lets an already-privileged administrator plant malicious HTML inside an identity name. When another admin later deletes that identity, the injected HTML renders in their browser, opening the door to phishing lures or redirects. Impact is limited because full script execution is blocked by input validation and Content Security Policy.
Executive priority
Schedule as a routine patch cycle item, not an emergency. The bug requires a trusted insider and yields only phishing-grade impact, but regulated and OT-heavy environments should prioritize the upgrade because Siemens has echoed the advisory and admin trust boundaries in monitoring platforms carry outsized reputational risk.
Technical view
Stored HTML injection (CWE-79) in the Credentials Manager of Nozomi Guardian and CMC before 26.1.0. An authenticated administrator can define an identity with unsanitized HTML tags that renders when a victim admin triggers the delete workflow. CVSS 3.1 base 5.9 (AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L). The vendor states CSP and existing input filters prevent full XSS and direct data exfiltration, constraining the attack to phishing and possible open redirect chains.
Likely exposure
Exposure is confined to organizations running Nozomi Guardian or CMC appliances at versions prior to 26.1.0 where multiple administrators share the Credentials Manager. Siemens has issued a coordinated advisory, suggesting overlap with industrial and OT environments that embed Nozomi sensors. Public-internet reach is not required, but multi-admin OT monitoring consoles are common in enterprise SOC and plant deployments.
Exploitation context
No public exploitation has been reported and the CVE is not on CISA KEV. Exploitation requires an already-authenticated administrator to plant the payload and a second administrator to perform the delete action, so it is realistic only in insider-threat or post-compromise scenarios. Impact is capped at phishing content or redirect abuse because CSP prevents script execution and direct data theft.
Researcher notes
Watch for the payload surface at the identity name/description field in Credentials Manager; rendering occurs on the delete confirmation flow. CSP is credited with blocking script execution, so validate CSP directives are unchanged post-upgrade and not weakened by customer overrides. Open redirect via anchor tags is plausible and worth including in test cases. No public PoC observed; monitor Nozomi and Siemens ProductCERT for updates.
Mitigation direction
- Upgrade Nozomi Guardian and CMC to version 26.1.0 or later per vendor advisory NN-2026:4-01.
- Apply Siemens SSA-827968 guidance for OT deployments bundling Nozomi sensors.
- Restrict Credentials Manager administrative rights to a minimal, audited set of accounts.
- Enforce multi-factor authentication and session monitoring on all Guardian and CMC admin logins.
- Review Credentials Manager entries for suspicious HTML or unexpected characters before upgrade.
Validation and detection
- Confirm installed Guardian or CMC build against the fixed version listed in NN-2026:4-01.
- Audit Credentials Manager identity records for tags, angle brackets, or embedded URLs.
- Review admin audit logs for unusual identity creation or edit events preceding deletions.
- Verify Content Security Policy headers remain enforced on Guardian and CMC web interfaces.
- Cross-check Siemens advisory SSA-827968 for any OEM-specific patched build numbers.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2025-40901 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.9 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L1.73.7NozomiCVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:L/VA:L/SC:L/SI:L/SA:L——NozomiVulnerability scoring details
Base CVSS 4.0 score
4.8MediumVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:L/VA:L/SC:L/SI:L/SA:L
Base CVSS 3.1 score
5.9MediumVector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://security.nozominetworks.com/NN-2026:4-01CVE reference, Nozomi
- https://cert-portal.siemens.com/productcert/html/ssa-827968.htmlCVE reference, siemens-SADP
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.