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Full vulnerability report · 2025
CVE-2025-20240High confidence

Cisco Cisco IOS XE Software: Incomplete Denylist to Cross-Site Scripting

Cisco · Cisco IOS XE Software

Official source article: Cisco CISCO-SA-WEBUI-XSS-VWYDGJOU ↗. Check the applicable product and release in the original source.

6.1MediumCVSS 3.1
Recommended action
Scheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Fix not verified
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:Medium, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • EPSS is 0.29% for the current model date.

Compensating controls

  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Cisco Cisco IOS XE Software and falls inside the recorded affected range.
  2. Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: As exposure requiresRemediation target: Within 365 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2025-31028

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionScheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Fix not verified
01

What, why and how

A vulnerability in the Web Authentication feature 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.

What

A vulnerability in the Web Authentication feature 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.

Why

The product uses a denylist-based protection mechanism to defend against XSS attacks, but the denylist is incomplete, allowing XSS variants to succeed.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

A vulnerability in the Web Authentication feature 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.

Why

The product uses a denylist-based protection mechanism to defend against XSS attacks, but the denylist is incomplete, allowing XSS variants to succeed.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Incomplete Denylist to Cross-Site Scripting → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
Required interaction required
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Changed: exploitation can affect a different security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-692 ↗

CWE-692: Incomplete Denylist to Cross-Site Scripting. The product uses a denylist-based protection mechanism to defend against XSS attacks, but the denylist is incomplete, allowing XSS variants to succeed.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SChangedScope: The attack can affect a component governed by a different security authority.CLowConfidentiality impact: A successful attack can cause a limited loss.ILowIntegrity impact: A successful attack can cause a limited loss.ANoneAvailability impact: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-692
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-2025-2124Cisco IOS und IOS XE: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Cisco IOS und Cisco IOS XE ausnutzen, um vertrauliche Informationen offenzulegen, Sicherheitsmaßnahmen zu umgehen, Cross-Site-Scripting-Angriffe durchzuführen, einen Denial-of-Service-Zustand zu verursachen und beliebigen Code auszuführen – sogar mit Root-Rechten.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20251001Security Bulletin 01 Oct 2025

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 01 Oct 2025, published on 1 October 2025. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
NCSC-NL · Dutch · NCSC-2025-0297Kwetsbaarheden verholpen in Cisco IOS en Cisco IOS XE Software

A vulnerability in Cisco IOS XE Software's web UI allows unauthenticated remote attackers to perform reflected cross-site scripting (XSS) attacks due to improper input sanitization, potentially enabling cookie theft.

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Fix not verified
Affected
Cisco IOS XE Software: 16.6.1, 16.6.2, 16.6.3, 16.6.4, 16.6.5, 16.6.4a, 16.6.5a, 16.6.6, 16.6.7, 16.6.8, 16.6.9, 16.6.10, 16.7.1, 16.7.1a, 16.7.1b, 16.7.2, 16.7.3, 16.7.4, 16.8.1, 16.8.1a, 16.8.1b, 16.8.1s, 16.8.1c, 16.8.1d, 16.8.2, 16.8.1e, 16.8.3, 16.9.1, 16.9.2, 16.9.1a, 16.9.1b, 16.9.1s, 16.9.3, 16.9.4, 16.9.3a, 16.9.5, 16.9.5f, 16.9.6, 16.9.7, 16.9.8, 16.10.1, 16.10.1a, 16.10.1b, 16.10.1s, 16.10.1c, 16.10.1e, 16.10.1d, 16.10.2, 16.10.1f, 16.10.1g, 16.10.3, 16.11.1, 16.11.1a, 16.11.1b, 16.11.2, 16.11.1s, 16.12.1, 16.12.1s, 16.12.1a, 16.12.1c, 16.12.1w, 16.12.2, 16.12.1y, 16.12.2a, 16.12.3, 16.12.8, 16.12.2s, 16.12.1x, 16.12.1t, 16.12.4, 16.12.3s, 16.12.3a, 16.12.4a, 16.12.5, 16.12.6, 16.12.1z1, 16.12.5a, 16.12.5b, 16.12.1z2, 16.12.6a, 16.12.7, 16.12.9, 16.12.10, 16.12.10a, 16.12.11, 16.12.12, 16.12.13, 17.1.1, 17.1.1a, 17.1.1s, 17.1.1t, 17.1.3, 17.2.1, 17.2.1r, 17.2.1a, 17.2.1v, 17.2.2, 17.2.3, 17.3.1, 17.3.2, 17.3.3, 17.3.1a, 17.3.1w, 17.3.2a, 17.3.1x, 17.3.1z, 17.3.4, 17.3.5, 17.3.4a, 17.3.6, 17.3.4b, 17.3.4c, 17.3.5a, 17.3.5b, 17.3.7, 17.3.8, 17.3.8a, 17.4.1, 17.4.2, 17.4.1a, 17.4.1b, 17.4.2a, 17.5.1, 17.5.1a, 17.6.1, 17.6.2, 17.6.1w, 17.6.1a, 17.6.1x, 17.6.3, 17.6.1y, 17.6.1z, 17.6.3a, 17.6.4, 17.6.1z1, 17.6.5, 17.6.6, 17.6.6a, 17.6.5a, 17.6.7, 17.6.8, 17.6.8a, 17.7.1, 17.7.1a, 17.7.1b, 17.7.2, 17.10.1, 17.10.1a, 17.10.1b, 17.8.1, 17.8.1a, 17.9.1, 17.9.1w, 17.9.2, 17.9.1a, 17.9.1x, 17.9.1y, 17.9.3, 17.9.2a, 17.9.1x1, 17.9.3a, 17.9.4, 17.9.1y1, 17.9.5, 17.9.4a, 17.9.5a, 17.9.5b, 17.9.6, 17.9.6a, 17.9.7, 17.9.5e, 17.9.5f, 17.9.7a, 17.9.7b, 17.11.1, 17.11.1a, 17.12.1, 17.12.1w, 17.12.1a, 17.12.1x, 17.12.2, 17.12.3, 17.12.2a, 17.12.1y, 17.12.1z, 17.12.4, 17.12.3a, 17.12.1z1, 17.12.1z2, 17.12.4a, 17.12.5, 17.12.4b, 17.12.1z3, 17.12.5a, 17.12.1z4, 17.12.5b, 17.12.5c, 17.13.1, 17.13.1a, 17.14.1, 17.14.1a, 17.15.1, 17.15.1w, 17.15.1a, 17.15.2, 17.15.1b, 17.15.1x, 17.15.3, 17.15.2c, 17.15.2a, 17.15.1y, 17.15.2b, 17.15.3a, 17.15.3b, 17.16.1, 17.16.1a
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 24 Sept 2025 · Last source change 26 Sept 2025, 17:12 UTC · CWE-692 · Incomplete Denylist to Cross-Site Scripting

CVE recordCVE.org · 5.1
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2025-31028
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD not scheduled

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    16.6.1; 16.6.2; 16.6.3; 16.6.4; 16.6.5; 16.6.4a; 16.6.5a; 16.6.6 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    Cisco IOS XE Software: 16.6.1, 16.6.2, 16.6.3, 16.6.4, 16.6.5, 16.6.4a, 16.6.5a, 16.6.6, 16.6.7, 16.6.8, 16.6.9, 16.6.10, 16.7.1, 16.7.1a, 16.7.1b, 16.7.2, 16.7.3, 16.7.4, 16.8.1, 16.8.1a, 16.8.1b, 16.8.1s, 16.8.1c, 16.8.1d, 16.8.2, 16.8.1e, 16.8.3, 16.9.1, 16.9.2, 16.9.1a, 16.9.1b, 16.9.1s, 16.9.3, 16.9.4, 16.9.3a, 16.9.5, 16.9.5f, 16.9.6, 16.9.7, 16.9.8, 16.10.1, 16.10.1a, 16.10.1b, 16.10.1s, 16.10.1c, 16.10.1e, 16.10.1d, 16.10.2, 16.10.1f, 16.10.1g, 16.10.3, 16.11.1, 16.11.1a, 16.11.1b, 16.11.2, 16.11.1s, 16.12.1, 16.12.1s, 16.12.1a, 16.12.1c, 16.12.1w, 16.12.2, 16.12.1y, 16.12.2a, 16.12.3, 16.12.8, 16.12.2s, 16.12.1x, 16.12.1t, 16.12.4, 16.12.3s, 16.12.3a, 16.12.4a, 16.12.5, 16.12.6, 16.12.1z1, 16.12.5a, 16.12.5b, 16.12.1z2, 16.12.6a, 16.12.7, 16.12.9, 16.12.10, 16.12.10a, 16.12.11, 16.12.12, 16.12.13, 17.1.1, 17.1.1a, 17.1.1s, 17.1.1t, 17.1.3, 17.2.1, 17.2.1r, 17.2.1a, 17.2.1v, 17.2.2, 17.2.3, 17.3.1, 17.3.2, 17.3.3, 17.3.1a, 17.3.1w, 17.3.2a, 17.3.1x, 17.3.1z, 17.3.4, 17.3.5, 17.3.4a, 17.3.6, 17.3.4b, 17.3.4c, 17.3.5a, 17.3.5b, 17.3.7, 17.3.8, 17.3.8a, 17.4.1, 17.4.2, 17.4.1a, 17.4.1b, 17.4.2a, 17.5.1, 17.5.1a, 17.6.1, 17.6.2, 17.6.1w, 17.6.1a, 17.6.1x, 17.6.3, 17.6.1y, 17.6.1z, 17.6.3a, 17.6.4, 17.6.1z1, 17.6.5, 17.6.6, 17.6.6a, 17.6.5a, 17.6.7, 17.6.8, 17.6.8a, 17.7.1, 17.7.1a, 17.7.1b, 17.7.2, 17.10.1, 17.10.1a, 17.10.1b, 17.8.1, 17.8.1a, 17.9.1, 17.9.1w, 17.9.2, 17.9.1a, 17.9.1x, 17.9.1y, 17.9.3, 17.9.2a, 17.9.1x1, 17.9.3a, 17.9.4, 17.9.1y1, 17.9.5, 17.9.4a, 17.9.5a, 17.9.5b, 17.9.6, 17.9.6a, 17.9.7, 17.9.5e, 17.9.5f, 17.9.7a, 17.9.7b, 17.11.1, 17.11.1a, 17.12.1, 17.12.1w, 17.12.1a, 17.12.1x, 17.12.2, 17.12.3, 17.12.2a, 17.12.1y, 17.12.1z, 17.12.4, 17.12.3a, 17.12.1z1, 17.12.1z2, 17.12.4a, 17.12.5, 17.12.4b, 17.12.1z3, 17.12.5a, 17.12.1z4, 17.12.5b, 17.12.5c, 17.13.1, 17.13.1a, 17.14.1, 17.14.1a, 17.15.1, 17.15.1w, 17.15.1a, 17.15.2, 17.15.1b, 17.15.1x, 17.15.3, 17.15.2c, 17.15.2a, 17.15.1y, 17.15.2b, 17.15.3a, 17.15.3b, 17.16.1, 17.16.1a · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
ENISA EUVD · EUVD-2025-31028↗CVE authority or vendor reference · Cisco CISCO-SA-WEBUI-XSS-VWYDGJOU↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2025-20240 · cve.blacktree.nl