Cisco Unity Connection: Server-Side Request Forgery
CVE-2026-20035 is a high-severity server-side request forgery vulnerability in Cisco Unity Connection from Cisco, with a CVSS 3.1 base score of 7.2 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Cisco Unity Connection versions: 12.5(1); 12.5(1)SU1; 12.5(1)SU2, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.3% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Unity Connection to 14.0 or a later version.
- Read the advisory on sec.cloudapps.cisco.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Cisco | Cisco Unity Connection | 12.5(1); 12.5(1)SU1; 12.5(1)SU2; 12.5(1)SU3; 12.5(1)SU4; 14; 12.5(1)SU5; 14SU1; and 13 more ranges | Not stated |
| Cisco | Unity Connection | before 14.0; 14.0; 14su1; 14su2; 14su3; 14su4; 15.0; 15su1; and 2 more ranges | 14.0 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- LowSome restricted data can be read.
- Integrity
- LowLimited modification of data is possible.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N. Scored by CNA (cisco.com).
Official description
A vulnerability in the web UI of Cisco Unity Connection Web Inbox could allow an unauthenticated, remote attacker to conduct SSRF attacks through an affected device. This vulnerability is due to improper input validation for specific HTTP requests. An attacker could exploit this vulnerability by sending a crafted HTTP request to an affected device. A successful exploit could allow the attacker to send arbitrary network requests that are sourced from the affected device.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Server-Side Request Forgery
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
How developers prevent this class of flaw
- If there is a known list of applications, IP, hostname, and/or domains to which the product is allowed to communicate, then use allowlists to ensure that outgoing requests are restricted to these known entities. The allowlists could be in the application code or possibly enforced by firewalls or network segmentation.
- If the product is expected to be able to connect to arbitrary IP addresses or domains, consider using a denylist that includes private network addresses, internal domain names, etc. The denylist could be in the application code or possibly enforced by firewalls or network segmentation.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in Cisco Unity Connection
- 7.5 High severity
- 7.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 9.3 Critical severity
Recent Server-Side Request Forgery vulnerabilities
- 8.6 High severity
- 7.2 High severity
- 7.5 High severity
- 8.3 High severity
- 8.6 High severity
- 7.7 High severity
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