Security readout for executives and security teams
Plain-English summary
CVE-2021-43549 affects OSIsoft PI Web API. An authenticated attacker with PI Server write access could lure a user into using a PI Web API endpoint that redirects them to a malicious site. The business risk is sensitive-information disclosure or users being shown false information in an operational technology context.
Executive priority
Treat as a moderate OT application risk. It is not presented as actively exploited, but it can affect trust in operational data and expose sensitive information if privileged internal access is abused.
Technical view
The issue is tracked as CWE-79 and has CVSS 3.1 score 6.9. Attack prerequisites are high privilege, network access, and user interaction. Scope changes because the impact can leave the PI Web API trust boundary through redirection, with high confidentiality impact and low integrity impact.
Likely exposure
Exposure is limited to environments running OSIsoft PI Web API, listed as all versions in the source bundle. Practical risk depends on whether authenticated users or service accounts have PI Server write access and whether users can be induced to interact with affected PI Web API endpoints.
Exploitation context
The provided sources do not state active exploitation, and the CVE is not marked KEV. Exploitation requires an authenticated attacker with write access to a PI Server plus victim interaction, which reduces broad internet-scale risk but remains important for OT environments with trusted internal users.
Researcher notes
Evidence is limited to the CVE description, CVSS vector, affected product statement, CWE mapping, and CISA advisory reference. The bundle does not name a specific fixed version, patch level, or confirmed exploit activity.
Mitigation direction
- Check CISA and vendor guidance for fixed versions or official mitigations.
- Restrict PI Server write access to only users and services that require it.
- Review PI Web API exposure and limit access to trusted networks where feasible.
- Warn users not to follow unexpected PI Web API links or prompts.
Validation and detection
- Inventory all OSIsoft PI Web API deployments and versions.
- Identify accounts with PI Server write access and confirm business need.
- Review whether PI Web API is reachable from untrusted networks.
- Check vendor or CISA advisory status for update and mitigation details.
- Look for reports of suspicious redirects or unusual user interactions.
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-2021-43549 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
- 6.9 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:L/A:N
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.
CVSS vector scores
1 official scoreWe 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:H/I:L/A:N1.74.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.9MediumVector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://us-cert.cisa.gov/ics/advisories/icsa-21-313-06CVE reference · x_refsource_MISC
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.