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Invalid certificates can be used to block access to the built-in server or Secure Desktop over remote for another user.

Low
seanbudd published GHSA-42v6-wjv6-h3jj Dec 4, 2025

Package

NVDA

Affected versions

2025.1-2025.3.1

Patched versions

2025.3.2

Description

Summary

Denial of service: Invalid certificates can be used to block access to the built-in server or Secure Desktop over remote for another user.
Impact: A local server can't be hosted, and a controlling computer can't work with the Secure Desktop over a remote connection.

Patch commit(s)

d9e5e05

Limitations

Remote Access needs to be enabled in NVDA's system config.

The first user to create the certificate has to be the one to exploit this.

Technical details

Proof of concept

  1. As user 1, start NVDA and host a local server.
  2. Disconnect.
  3. Find NvdaRemoteRelay.key in c:\ProgramData\temp and replace it with an empty directory.
  4. Host a server, either as user 1 or another user. It will fail with:
ERROR - unhandled exception (02:14:46.760) - MainThread (4748):
Traceback (most recent call last):
  File "wx\core.pyc", line 3427, in <lambda>
  File "gui\__init__.pyc", line 926, in run
  File "_remoteClient\client.pyc", line 341, in handleDialogCompletion
  File "_remoteClient\client.pyc", line 483, in startControlServer
  File "_remoteClient\server.pyc", line 265, in __init__
  File "_remoteClient\server.pyc", line 87, in ensureValidCertExists
  File "_remoteClient\server.pyc", line 173, in _generateSelfSignedCert
PermissionError: [Errno 13] Permission denied: 'C:\\ProgramData\\temp\\NvdaRemoteRelay.key'

Remote will also not work on the Secure Desktop, because the server is needed there.

Indicators of compromise

Attempting to create a Remote Access connection with a self-hosted server will fail.

Workarounds

Unknown

Timeline

history of the disclosure and release process

  • Reported: 2025/09/30
  • Acknowledged by NV Access: 2025/10/07
  • Fix released - NVDA 2025.3.2: 2025/11/24
  • Disclosed: 2025/12/4

For more information

If you have any questions or comments about this advisory:

Severity

Low

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Local
Attack Complexity Low
Attack Requirements Present
Privileges Required Low
User interaction None
Vulnerable System Impact Metrics
Confidentiality None
Integrity Low
Availability Low
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N

CVE ID

No known CVE

Weaknesses

No CWEs