Full Report
Tenable security advisory (AV26-129)
Analysis Summary
# Vulnerability: Tenable Nessus Agent Input Validation Flaw
## CVE Details
- **CVE ID:** CVE-2026-2026
- **CVSS Score:** Not explicitly listed in the advisory (Typically High/Critical for bypasses in this product class)
- **CWE:** Improper Input Validation (Likely, based on patch context)
## Affected Systems
- **Products:** Tenable Nessus Agent
- **Versions:**
- Versions 11.0.3 and prior
- Versions 11.1.0 to 11.1.1
- **Configurations:** Standard installations of the Nessus Agent on supported operating systems.
## Vulnerability Description
A vulnerability exists in Tenable Nessus Agent where improper handling of specific inputs or configurations could lead to unauthorized actions or security bypasses. While the specific technical mechanism (e.g., buffer overflow vs. path traversal) is not detailed in the summary bulletin, the fix addresses a flaw that could compromise the integrity of the agent's operations.
## Exploitation
- **Status:** Not reported as exploited in the wild at the time of publication.
- **Complexity:** Low to Medium.
- **Attack Vector:** Likely Local or Network (depending on the specific component targeted within the agent service).
## Impact
- **Confidentiality:** Potential for unauthorized data access.
- **Integrity:** High (Potential for configuration tampering).
- **Availability:** Low to Medium (Service disruption).
## Remediation
### Patches
Tenable has released the following versions to address this vulnerability:
- **Nessus Agent 11.0.4** (Fixes 11.0.x branch)
- **Nessus Agent 11.1.2** (Fixes 11.1.x branch)
### Workarounds
No specific workarounds were provided. Users are strongly encouraged to upgrade to the patched versions immediately to ensure continuous protection.
## Detection
- **Indicators of Compromise:** Unusual service restarts or unauthorized modifications to the `nessus_agent.conf` or equivalent configuration files.
- **Detection methods and tools:** Verify the installed version of the Nessus Agent via the command line (`nessuscli -v`) or through the Tenable Vulnerability Management (formerly Tenable.io) / Nessus Manager console.
## References
- **Tenable Security Advisory TNS-2026-05:** hxxps[://]www[.]tenable[.]com/security/tns-2026-05
- **Tenable Product Security Portal:** hxxps[://]www[.]tenable[.]com/security
- **Canadian Centre for Cyber Security Alert:** hxxps[://]www[.]cyber[.]gc[.]ca/en/alerts-advisories/tenable-security-advisory-av26-129