Desk Phone 9871 FirmwareOperating system · Cisco
CVE-2025-20351
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 the web UI of Cisco Desk Phone 9800 Series, Cisco IP Phone 7800 and 8800 Series, and Cisco Video Phone 8875 running Cisco SIP Software could allow an unauthenticated, remote attacker to conduct XSS attacks against a user of the web UI. This vulnerability exists because the web UI of an affected device does not sufficiently validate user-supplied input. An attacker could exploit this vulnerability by persuading a user to click a crafted link. A successful exploit could allow the attacker to execute arbitrary script code in the context of the affected interface or access sensitive, browser-based information. Note: To exploit this vulnerability, the phone must be registered to Cisco Unified Communications Manager and have Web Access enabled. Web Access is disabled by default.
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 · moderate confidenceThis is a reflected XSS vulnerability in the web UI of Cisco Desk Phone 9800 Series, Cisco IP Phone 7800/8800 Series, and Cisco Video Phone 8875 running Cisco SIP Software. The vulnerability stems from insufficient validation of user-supplied input in the web interface, allowing attackers to inject malicious scripts via crafted URLs that execute in the context of the affected interface when users click the link.
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
Desk Phone 9871 FirmwareOperating system
>= 3.0\(1\), <= 3.2\(1\)
Desk Phone 9841 FirmwareOperating system
>= 3.0\(1\), <= 3.2\(1\)
Desk Phone 9851 FirmwareOperating system
>= 3.0\(1\), <= 3.2\(1\)
Desk Phone 9861 FirmwareOperating system
>= 3.0\(1\), <= 3.2\(1\)
Ip Phone 8865 FirmwareOperating system
< 14.3\(1\)= 14.3\(1\)
Ip Phone 7811 FirmwareOperating system
< 14.3\(1\)= 14.3\(1\)
Ip Phone 7821 FirmwareOperating system
< 14.3\(1\)= 14.3\(1\)
Ip Phone 7841 FirmwareOperating system
< 14.3\(1\)= 14.3\(1\)CVSS 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
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
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.
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Identify phone modelLocate the model number on the physical device label or check via the phone's admin web interface (typically at https://<phone-ip>/) under Device Information or similar sectionAffected if Model is Cisco Desk Phone 9841, 9851, 9861, 9871, or Cisco IP Phone 7811, 7821, 7841, or 8865
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Check firmware version on Desk Phones (9841/9851/9861/9871)Access the phone's web UI, navigate to Device Information or Administration section, and record the Firmware Version displayedAffected if Version is 3.0(1) through 3.2(1) inclusive (e.g., 3.0(1), 3.1(2), 3.2(1))
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Check firmware version on IP Phones (7811/7821/7841/8865)Access the phone's web UI, navigate to Device Information or Administration section, and record the Firmware Version displayedAffected if Version is less than 14.3(1) or exactly 14.3(1) (e.g., 14.2(3), 14.3(1))
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Verify if Web Access is enabledIn the phone's web UI, go to Network Setup or Administration settings and locate the Web Server or HTTP Server configuration option. Check if it is set to Enabled or if web access is permittedAffected if Web Access is enabled on the phone; if it is disabled (the default), the vulnerability cannot be exploited
Your environment is affected if you have a listed phone model running an affected firmware version AND have Web Access enabled in the phone settings.
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.
From vendor data14.3
Disable Web Access on affected phones if not required (it is disabled by default), and apply any available Cisco firmware patches for Cisco SIP Software when released. Until patches are available, consider network segmentation to limit exposure to phones with Web Access enabled.
Fix this in Desk Phone 9871 Firmware
Scoped from the published advisory
- Consultation4.0 h
- Implementation3.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,440.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-20351 — 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-2025-20351 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
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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