Identity Services EngineApplication · Cisco
CVE-2025-20124
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceCisco ISE contains an insecure deserialization vulnerability in an API endpoint where user-supplied Java byte streams are processed without proper validation. An attacker with read-only administrative credentials can send a crafted serialized Java object (likely leveraging known gadget chains) to achieve arbitrary command execution with root privileges on the affected device.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Identity Services EngineApplication
< 3.1= 3.1.0= 3.2.0= 3.3.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
-
Identify Cisco ISE installation and versionAccess the Cisco ISE admin web interface or use the CLI to retrieve the installed version. On the CLI, this is typically found via 'show version' or through the admin portal under Administration > System > Settings > System Configuration. Compare the version number to the affected ranges: versions < 3.1, 3.1.0, 3.2.0, and 3.3.0 are vulnerable.Affected if The installed version matches any of the vulnerable versions listed (less than 3.1, or exactly 3.1.0, 3.2.0, or 3.3.0).
-
Verify the API endpoint is network accessibleDetermine if the Cisco ISE admin interface or API ports (typically 443/https) are exposed to untrusted networks. Check firewall rules, ACLs, or network segmentation configurations that control access to the ISE management interfaces.Affected if The API endpoint is reachable from networks outside the trusted administrative IP range.
-
Review administrative account activityExamine Cisco ISE logs and audit trails for any suspicious API calls or administrative actions, particularly from accounts with read-only administrative privileges. Look for unexpected serialized Java object transmissions or unusual endpoint access patterns.Affected if There is evidence of API requests containing serialized data from unexpected sources or unusual command execution patterns in logs.
-
Check for unauthorized command executionReview system logs, process execution history, and any available forensic artifacts on the ISE device for signs of arbitrary command execution, particularly commands run as root or outside normal administrative workflows.Affected if Commands appear to have been executed with root privileges that were not initiated by known administrators through normal interfaces.
A system is affected if it runs a vulnerable Cisco ISE version (3.1.0, 3.2.0, 3.3.0, or any version below 3.1) AND the API endpoint is accessible to an attacker with read-only administrative credentials.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped3.1
Apply the vendor patch when released; until then, restrict network access to the affected API to trusted administrative IPs only, monitor for suspicious serialized object traffic, and consider disabling non-essential API endpoints.
Cisco ISE 3.4.0 or later
- 1. Verify current Cisco ISE version by navigating to Administration > System > Licensing > Software Version or using the CLI command 'show version'
- 2. Schedule a maintenance window for the upgrade (note: in single-node deployments, new devices cannot authenticate during reload time as noted in CVE description)
- 3. Back up the Cisco ISE configuration using the admin UI (Administration > System > Backup & Restore) or CLI 'ise backup' command
- 4. Download the fixed Cisco ISE version (3.4.0 or later) from Cisco.com software download center
- 5. Upload the upgrade bundle via Administration > System > Maintenance > Software Update > Upload
- 6. Run the upgrade following Cisco ISE upgrade procedure documentation
- 7. After upgrade completes, verify the new version is running: Administration > System > Licensing > Software Version
- 8. Test that administrative API access works correctly with existing credentials
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Identity Services Engine
Scoped from the published advisory
- Consultation6.0 h
- Implementation10.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $7,872.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-20124 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2025-20124 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data