Security readout for executives and security teams
Plain-English summary
CVE-2021-1594 affects Cisco Identity Services Engine. In a specific man-in-the-middle scenario, an attacker who can decrypt HTTPS traffic between separate ISE nodes could modify internode API communications and gain root-level command execution. The impact is severe, but the required position and HTTPS decryption make exploitation harder than a simple internet-facing bug.
Executive priority
Treat this as a high-priority infrastructure risk for Cisco ISE environments, especially multi-node deployments. The exploitation prerequisites reduce likelihood, but successful compromise would give root access to a security control platform that may affect authentication and network access decisions.
Technical view
The Cisco ISE REST API lacked sufficient input validation on specific internode endpoints. An unauthenticated remote attacker positioned between ISE personas on separate nodes could alter decrypted HTTPS communications, trigger command injection, and execute arbitrary commands as root. CVSS 3.1 is 7.5 with high confidentiality, integrity, and availability impact and high attack complexity.
Likely exposure
Exposure is most relevant to organizations running Cisco ISE Software in multi-node deployments where ISE personas communicate across network paths an attacker could intercept. The bundle does not provide affected version ranges, so product owners must confirm exposure against Cisco’s advisory and their deployed ISE versions.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation. Exploitation requires a man-in-the-middle position and the ability to decrypt HTTPS traffic between ISE personas on separate nodes, which materially narrows practical attack scenarios but still threatens full system compromise.
Researcher notes
Key uncertainty is version applicability: the source bundle lists Cisco ISE Software but no affected or fixed version details. Analysis should stay anchored to Cisco’s advisory. Do not infer internet-wide exploitability; the described path depends on decrypted internode HTTPS traffic and attacker positioning.
Mitigation direction
- Review Cisco’s advisory for affected and fixed ISE release information.
- Upgrade or apply only Cisco-recommended remediations for deployed ISE versions.
- Restrict and monitor network paths used for ISE internode communications.
- Investigate weaknesses that could allow HTTPS decryption between ISE nodes.
Validation and detection
- Inventory Cisco ISE deployments and identify multi-node persona communication paths.
- Compare deployed ISE versions with Cisco advisory guidance.
- Review logs for suspicious internode API activity or unexpected root-level command execution.
- Confirm TLS trust, certificate handling, and internode traffic protections are operating as intended.
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
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CWE-266: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. 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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupPrivilege behavior lookup
The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-1594 mapping review
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Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
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:H/PR:N/UI:R/S:U/C:H/I:H/A:H1.65.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- 20211006 Cisco Identity Services Engine Privilege Escalation VulnerabilityCVE reference · vendor-advisory, x_refsource_CISCO
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.
Incorrect Privilege Assignment
Incorrect Privilege Assignment represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.