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Cisco Vulnerabilities Exploited CVE-2025-20281 & CVE-2025-20337

July 24, 2025 | 2 MINS READ

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THE THREAT

On July 21st, 2025, Cisco confirmed attempted exploitation of recently disclosed maximum severity vulnerabilities impacting its Identity Services Engine (ISE) and ISE Passive Identity Connector (ISE-PIC).

CVE-2025-20281 (CVSS: 10) and CVE-2025-20337 (CVSS: 10) are vulnerabilities in a specific API of the impacted Cisco products and can allow an unauthenticated, remote attacker to execute arbitrary code with root privileges. Successful exploitation of these vulnerabilities could result in pre-authenticated Remote Code Execution (RCE) on impacted systems leading to full system compromise, unauthorized access to sensitive data, or disruption of critical network services.

Trend Micro’s Zero Day Initiative, which originally reported the vulnerabilities to Cisco, confirmed they observed the exploitation of CVE-2025-20281 on July 17th, 2025. Due to the similarities between CVE-2025-20281 and CVE-2025-20337, Trend Micro believes that CVE-2025-20337 is also likely to be exploited. The observed attacks are currently limited in scope and appear to be highly targeted in nature.

Given the severity of the vulnerabilities and confirmed exploitation of at least one vulnerability, it is critical for organizations to apply recommended security patches immediately.

What we’re doing about it

What you should do about it

Additional information

Cisco initially disclosed two critical vulnerabilities, CVE-2025-20281 and CVE-2025-20282 on June 25th, 2025. The advisory was updated on July 16th, to include CVE-2025-20337. CVE-2025-20281 and CVE-2025-20337 are due to insufficient validation of user-supplied input. To exploit the vulnerabilities, a remote, unauthenticated attacker can submit specially crafted API requests and obtain root privileges on an affected device. Exploitation of these flaws would result in pre-authentication RCE, offering attackers a low-barrier, high-impact entry point into critical systems.

The third vulnerability disclosed in the security advisory is CVE-2025-20282 (CVSS: 10) that affects an internal API in the impacted Cisco products and can allow an unauthenticated, remote attacker to upload and execute arbitrary files with root privileges. The flaw stems from insufficient file validation checks, allowing attackers to upload malicious files to privileged directories on the affected system.

Cisco's update on July 21st, 2025, did not specify which vulnerabilities were targeted in the attempted exploitation. However, the company strongly recommended that organizations upgrade to secure versions of the affected products to mitigate potential risks. Trend Micro’s confirmation of active exploitation of CVE-2025-20281 underscores the urgent need for organizations to patch affected systems without delay. Although there have been no reports of CVE-2025-20337 being exploited, it is believed to be under active exploitation due to its similarities with the confirmed exploited vulnerability. According to Trend Micro’s update, exploitation has been observed only in a small number of targeted attacks. It is highly likely that following the public disclosure of ongoing exploitation, threat actors will escalate their efforts, potentially leading to large-scale targeting while organizations work to patch vulnerable systems.

To avoid potential disruption caused by exploitation of vulnerabilities in Cisco products, it is critical that organizations promptly apply the relevant patches.

Impacted Versions List:

References:

[1] https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ise-unauth-rce-ZAd2GnJ6
[2] https://nvd.nist.gov/vuln/detail/CVE-2025-20281
[3] https://nvd.nist.gov/vuln/detail/CVE-2025-20282
[4] https://nvd.nist.gov/vuln/detail/CVE-2025-20337
[5] https://cyberscoop.com/cisco-identity-services-engines-active-exploits/

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