CVE-2026-72529: TrueConf Server Missing Authentication for Critical Function Vulnerability

In short

TrueConf Server has a weakness classified as missing authentication for critical function (CWE-306). CISA added it to its Known Exploited Vulnerabilities catalog on 2026-08-20. NVD lists CVSS 4.0 at 9.3 CRITICAL.

What it is

“TrueConf Server contains a missing authentication for critical function vulnerability which could allow a remote unauthorized attacker with network access via port 4307/TCP to execute an arbitrary script.” — CISA KEV, retrieved 2026-11-01

“A remote unauthorized attacker with network access via port 4307/TCP to the TrueConf server versions 5.3.X to 5.3.9, 5.4.X to 5.4.9, 5.5.X to 5.5.5, and earlier could execute an arbitrary script by calling an undocumented function.” — NVD, retrieved 2026-11-01

Who is affected

TrueConf Server. NVD lists the following versions as affected:

• Versions before 5.3.9.10013
• Versions before 5.3.9.10015
• Versions from 5.4.0.12689 inclusive, before 5.4.9.10072
• Versions from 5.4.0.12700 inclusive, before 5.4.9.10019
• Versions from 5.5.0.13826 inclusive, before 5.5.5.10010
• Versions from 5.5.0.13828 inclusive, before 5.5.5.10009

Exploitation status

CISA KEV added: 2026-08-20. Known ransomware campaign use: Not reported by CISA. Due date CISA set for US federal civilian agencies: 2026-08-23.

Scores

NVD CVSS 4.0: 9.3 CRITICAL; vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source [email protected].

EPSS by FIRST: 1.46%; percentile 73.65; score date 2026-10-31. EPSS estimates the probability of exploitation in the next 30 days.

CWE: CWE-306.

Timeline

CISA required action

“Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.” — CISA KEV

What to do

• Confirm whether you run TrueConf Server and which version.
• Apply the vendor update or mitigation in the vendor advisory.
• Follow CISA’s required action.
• Review the vendor guidance on signs of compromise.
• Track the fix through completion.

References

• Third Party Advisory: https://ics-cert.kaspersky.com/advisories/2026/08/11/trueconf-server-missing-authentication-for-critical-function/
• NVD detail
• CVE.org record
• CISA KEV catalog

Sources and dates

CISA Known Exploited Vulnerabilities Catalog, version 2026.10.30; retrieved 2026-11-01. CISA KEV data: CC0 1.0. No endorsement by CISA.

NVD retrieved: 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.

EPSS scores by FIRST; score date 2026-10-31.