Cisco IOS XE up to 17.16.1a Web UI incomplete denylist to cross-site scripting

CVSS Meta Temp Score
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CTI Interest Score
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5.1$5k-$25k0.00

Summaryinfo

A vulnerability marked as problematic has been reported in Cisco IOS XE. This impacts an unknown function of the component Web UI. The manipulation leads to incomplete denylist to cross-site scripting. This vulnerability is listed as CVE-2025-20240. The attack may be initiated remotely. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Cisco IOS XE. It has been rated as problematic. This issue affects an unknown code of the component Web UI. The manipulation with an unknown input leads to a incomplete denylist to cross-site scripting vulnerability. Using CWE to declare the problem leads to CWE-692. The product uses a denylist-based protection mechanism to defend against XSS attacks, but the denylist is incomplete, allowing XSS variants to succeed. Impacted is integrity. The summary by CVE is:

A vulnerability in the web UI of Cisco IOS XE Software could allow an unauthenticated, remote attacker to conduct a reflected cross-site scripting attack (XSS) on an affected device. This vulnerability is due to improper sanitization of user-supplied input. An attacker could exploit this vulnerability by persuading a user to click a malicious link. A successful exploit could allow the attacker to execute a reflected XSS attack and steal user cookies from the affected device.

It is possible to read the advisory at sec.cloudapps.cisco.com. The identification of this vulnerability is CVE-2025-20240 since 10/10/2024. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 09/24/2025).

Upgrading eliminates this vulnerability.

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Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.2
VulDB Meta Temp Score: 5.1

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 6.1
CNA Vector (cisco): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Incomplete denylist to cross-site scripting
CWE: CWE-692 / CWE-79 / CWE-94
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Timelineinfo

10/10/2024 CVE reserved
09/24/2025 +349 days Advisory disclosed
09/24/2025 +0 days VulDB entry created
09/24/2025 +0 days VulDB entry last update

Sourcesinfo

Vendor: cisco.com

Advisory: cisco-sa-webui-xss-VWyDgjOU
Status: Confirmed

CVE: CVE-2025-20240 (🔒)
GCVE (CVE): GCVE-0-2025-20240
GCVE (VulDB): GCVE-100-325763
scip Labs: https://www.scip.ch/en/?labs.20150108

Entryinfo

Created: 09/24/2025 19:29
Changes: 09/24/2025 19:29 (64)
Complete: 🔍
Cache ID: 216::103

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