CVE-2026-5923 Overview
CVE-2026-5923 is a Cross-Site Request Forgery (CSRF) vulnerability [CWE-352] affecting an HP IP phone web management interface. An attacker who obtains a valid session cookie can leverage it to modify the contents of the IP phone's webpage. The flaw allows unauthorized state-changing requests to be issued against the device on behalf of an authenticated user. Exploitation requires network access, low privileges, and user interaction, according to the CVSS 4.0 vector.
Critical Impact
Successful exploitation permits an attacker to alter IP phone webpage content, undermining the integrity of device configuration and administrative interfaces.
Affected Products
- HP IP phone (see the HP Security Bulletin for specific models and firmware versions)
Discovery Timeline
- 2026-07-08 - CVE-2026-5923 published to the National Vulnerability Database
- 2026-07-08 - Last updated in NVD database
Technical Details for CVE-2026-5923
Vulnerability Analysis
The vulnerability stems from missing anti-CSRF protections in the IP phone's web management interface. When a legitimate administrator authenticates to the device, the resulting session cookie can be reused by an attacker to submit forged requests. The application accepts these requests as valid because no additional token or origin validation is performed.
An attacker who steals or replays a session cookie can then push arbitrary changes to the phone's webpage content. This can be leveraged to alter administrative pages, plant misleading information, or stage follow-on attacks against operators viewing the device UI.
Root Cause
The root cause is the absence of a per-request CSRF token and insufficient validation of request origin on state-changing endpoints. The web application trusts cookie-based session authentication alone to authorize page modifications. This design does not defend against stolen or forced cookie reuse.
Attack Vector
Exploitation is network-based and requires an authenticated session context. The attacker must obtain a valid cookie, typically through phishing, network interception, or a companion browser-side flaw, and induce a request to the vulnerable endpoint. The vulnerability affects the integrity and availability of the device's web content while confidentiality impact remains limited.
No verified proof-of-concept code has been published. Refer to the HP Security Bulletin for vendor-supplied technical detail.
Detection Methods for CVE-2026-5923
Indicators of Compromise
- Unexpected modifications to IP phone webpage content or administrative banners
- HTTP POST or PUT requests to the phone's management interface originating from external referrers
- Session cookies for the phone's admin interface appearing in requests from unusual client IP addresses
- Configuration changes in device logs that do not correlate with authorized administrator activity
Detection Strategies
- Inspect web server access logs on the IP phone or upstream proxy for state-changing requests lacking a same-origin referrer
- Correlate administrator login events with subsequent configuration changes to identify off-hours or anomalous modifications
- Monitor for reuse of a single session cookie across multiple source IP addresses within a short interval
Monitoring Recommendations
- Forward IP phone and VoIP management logs to a centralized SIEM for continuous review
- Alert on any successful POST to phone administration endpoints from outside the management VLAN
- Track integrity of the phone's web UI content through periodic hash comparison of rendered pages
How to Mitigate CVE-2026-5923
Immediate Actions Required
- Apply the firmware update referenced in the HP Security Bulletin to all affected IP phones
- Restrict access to phone administration interfaces to a dedicated management VLAN
- Force administrators to log out of the web interface when not actively managing devices to invalidate lingering session cookies
- Rotate any session cookies suspected of exposure and reset administrative credentials
Patch Information
HP has published guidance in the HP Security Bulletin. Administrators should consult the bulletin for the specific firmware versions containing the fix and follow HP's upgrade procedure for each affected model.
Workarounds
- Isolate IP phones from general user network segments and block direct browser access from workstations
- Require administrators to use short-lived sessions and close browser tabs immediately after configuration changes
- Enforce browser policies that prevent third-party sites from initiating requests to internal management interfaces
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
