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VulnerabilityPublished Updated

CVE-2025-20124: Cisco Identity Services Engine Software · Deserialization of Untrusted Data

Affects Cisco Identity Services Engine SoftwareSource CVE Database V5

0

Public exploit available (Exploit-DB) · 18% EPSS · CVSS 9.9 Critical.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.1 base score
9.9Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
18.4% chance of exploitation in 30 days – higher than 97% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:H/A:H

Exploitation evidence

t = 0 is the CVE’s publication on cve.org

  1. Disclosed: evidence found.

    CVE published 5 Feb 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  4. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

Timeline

  1. CVE ID reserved

    by Cisco Systems, Inc.

    , 118 days before disclosure

  2. CVE published

    on cve.org

    , t = 0

  3. First Exploit-DB entry (opens in a new tab)

    Cisco ISE 3.0 - Remote Code Execution (RCE)

    , 187 days after disclosure

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Cisco Cisco Identity Services Engine SoftwareAffected
  • 2.7.0 – 3.3.0
5 affected builds
Fixed in–

AI-suggested

  1. Immediately apply Cisco's security patches or updates addressing CVE-2025-20124 once available. Monitor Cisco advisories for official patches.
  2. Restrict and audit administrative access to Cisco ISE, enforcing strong authentication mechanisms such as multi-factor authentication (MFA) to reduce the risk of credential compromise.
  3. Limit network access to Cisco ISE management interfaces to trusted IP addresses and networks using firewall rules and segmentation.
  4. Monitor logs and network traffic for unusual API calls or serialized object submissions that could indicate exploitation attempts.
  5. Implement strict credential management policies, including regular rotation and revocation of unused or compromised credentials.
  6. Consider deploying Cisco ISE in high-availability or multi-node configurations to mitigate service disruption risks during reloads or attacks.
  7. Conduct regular security assessments and penetration testing focused on deserialization vulnerabilities and privilege escalation paths within Cisco ISE environments.
  8. Educate administrators about the risks of deserialization vulnerabilities and the importance of safeguarding administrative credentials.

Description

A vulnerability in an API of Cisco ISE could allow an authenticated, remote attacker to execute arbitrary commands as the root user on an affected device. This vulnerability is due to insecure deserialization of user-supplied Java byte streams by the affected software. An attacker could exploit this vulnerability by sending a crafted serialized Java object to an affected API. A successful exploit could allow the attacker to execute arbitrary commands on the device and elevate privileges. Note: To successfully exploit this vulnerability, the attacker must have valid read-only administrative credentials. In a single-node deployment, new devices will not be able to authenticate during the reload time.

References

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