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NVD / CVE Program· CNA cisco

CVE-2021-1594: Cisco Identity Services Engine Privilege Escalation Vulnerability

HighCVSS 8.1 · v3.1—No exploit No fix recorded

Noroxi assessment

Priority: Monitor (action score 32/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 1.3% (FIRST EPSS); higher than 72.8% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
  • According to the record, no fixed version is available yet.

Low priority for now. Update when a fix is released; follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

A vulnerability in the REST API of Cisco Identity Services Engine (ISE) could allow an unauthenticated, remote attacker to perform a command injection attack and elevate privileges to root. This vulnerability is due to insufficient input validation for specific API endpoints. An attacker in a man-in-the-middle position could exploit this vulnerability by intercepting and modifying specific internode communications from one ISE persona to another ISE persona. A successful exploit could allow the attacker to run arbitrary commands with root privileges on the underlying operating system. To exploit this vulnerability, the attacker would need to decrypt HTTPS traffic between two ISE personas that are located on separate nodes.

Published
Oct 6, 2021
Updated
Jun 16, 2026
EPSS
1.3% · 72th percentile

Report tools

JSON

Action score

32

Monitor

Low priority for now.

CVSS
32 / 40 · 8.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.3%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
8.1
CNA · cisco
7.5
0.6 point gap

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-1594

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
ciscoidentity services engine

Versions reported by the vendor

Affected version ranges reported by the assigning authority (cisco). Independent of NVD's CPE analysis and usually ahead of it.

  • Cisco Cisco Identity Services Engine Software

    • n/aaffected
Affected versions · NVD (9)

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • cisco identity services engine2.4.0 and later · before 2.6.0
  • cisco identity services engine2.4(0.902)
  • cisco identity services engine2.6.0
  • cisco identity services engine2.6(0.156)
  • cisco identity services engine2.7.0
  • cisco identity services engine2.7(0.903)
  • cisco identity services engine3.0.0
  • cisco identity services engine3.0(0.458)
  • cisco identity services engine3.1(0.440)

Same product

cisco: all records

Other highest-scoring records for the same primary product.

  • CVE-2025-20281Cisco ISE API Unauthenticated Remote Code Execution VulnerabilityKEV
    99Now
  • CVE-2026-76460Cisco Identity Services Engine Authentication Bypass VulnerabilityKEV
    93Now
  • CVE-2025-20337Cisco ISE API Unauthenticated Remote Code Execution VulnerabilityKEV
    92Now

Published before and after this one in the same product

  • ← EarlierCVE-2021-1607Jul 8, 2021 · Cisco Identity Services Engine Stored Cross-Site Scripting Vulnerabilities
    19Monitor
  • ← EarlierCVE-2021-34759Sep 1, 2021 · Cisco Identity Services Engine Cross-Site Scripting Vulnerability
    19Monitor
  • Later →CVE-2021-34702Oct 6, 2021 · Cisco Identity Services Engine Sensitive Information Disclosure Vulnerability
    17Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-266 · Incorrect Privilege Assignment

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records