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Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Access control enforcement
MITRE ATT&CK

1 technique across 1 tactic: Defense Evasion

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

CVSS score of 5.3 (MEDIUM). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required. EPSS exploitation probability: 0.06%.

Exploit ScenarioDerived

This vulnerability can be exploited remotely over the network. Successful exploitation could compromise the medium-severity affected system.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 28, 2026

A vulnerability in the directory permissions of Cisco Desk Phone 9800 Series, Cisco IP Phone 7800 and 8800 Series, and Cisco Video Phone 8875 could allow an unauthenticated, remote attacker to write. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified under CWE-284. A vulnerability in the directory permissions of Cisco Desk Phone 9800 Series, Cisco IP Phone 7800 and 8800 Series, and Cisco Video Phone 8875 could allow an unauthenticated, remote attacker to write arbitrary files on an affected device. This vulnerability is due to a lack of proper authentication controls. An attacker could exploit this vulnerability by sending a crafted request to an affected device. A successful exploit could allow the attacker to perform arbitrary file writes to specific directories in the underlying operating system. Note: To exploit this vulnerability, Web Access must be enabled on the phone. Web Access is disabled by default. Affected products include: Cisco Desk Phone 9841 Firmware, Cisco Desk Phone 9851 Firmware, Cisco Desk Phone 9861 Firmware, Cisco Desk Phone 9871 Firmware, Cisco Ip Phone 7811 Firmware.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 5.3 MEDIUM
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

DescriptionCVE.org

A vulnerability in the directory permissions of Cisco Desk Phone 9800 Series, Cisco IP Phone 7800 and 8800 Series, and Cisco Video Phone 8875 could allow an unauthenticated, remote attacker to write arbitrary files on an affected device.

This vulnerability is due to a lack of proper authentication controls. An attacker could exploit this vulnerability by sending a crafted request to an affected device. A successful exploit could allow the attacker to perform arbitrary file writes to specific directories in the underlying operating system. Note: To exploit this vulnerability, Web Access must be enabled on the phone. Web Access is disabled by default.

Executive ViewAI

Why It Matters

CVE-2025-20335 presents moderate security risk, a improper access control vulnerability rated CVSS 5.3. Exploitation could compromise the security of affected deployments. Organizations should apply vendor updates when available and monitor for exploitation.

Business Impact: Low
Compensating Controls

Apply vendor patch. If patching is delayed: restrict network access and enable monitoring.

Threat Intelligence Overview

EPSS Score
0.1%
Top 83% exploitable

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.1%
Patch available No
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact
Low

Priority Score

26
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +26
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

Affected Products (CPE)CVE.org

cpe:2.3:o:cisco:desk_phone_9841_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:cisco:desk_phone_9851_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:cisco:desk_phone_9861_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:cisco:desk_phone_9871_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ip_phone_7811_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ip_phone_7811_firmware:14.3\(1\):-:*:*:*:*:*:*
cpe:2.3:o:cisco:ip_phone_7811_firmware:14.3\(1\):sr1:*:*:*:*:*:*
cpe:2.3:o:cisco:ip_phone_7821_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ip_phone_7821_firmware:14.3\(1\):-:*:*:*:*:*:*
cpe:2.3:o:cisco:ip_phone_7821_firmware:14.3\(1\):sr1:*:*:*:*:*:*
cpe:2.3:o:cisco:ip_phone_7841_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ip_phone_7841_firmware:14.3\(1\):-:*:*:*:*:*:*
cpe:2.3:o:cisco:ip_phone_7841_firmware:14.3\(1\):sr1:*:*:*:*:*:*
cpe:2.3:o:cisco:ip_phone_7861_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ip_phone_7861_firmware:14.3\(1\):-:*:*:*:*:*:*
cpe:2.3:o:cisco:ip_phone_7861_firmware:14.3\(1\):sr1:*:*:*:*:*:*
cpe:2.3:o:cisco:ip_phone_8811_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ip_phone_8811_firmware:14.3\(1\):-:*:*:*:*:*:*
cpe:2.3:o:cisco:ip_phone_8811_firmware:14.3\(1\):sr1:*:*:*:*:*:*
cpe:2.3:o:cisco:ip_phone_8841_firmware:*:*:*:*:*:*:*:*
+ 28 more

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