CriticalCVE-2026-72530

    TrueConf Server Code Injection Vulnerability (CVE-2026-72530)

    Published Last modified In CISA KEV since Sources: pwn.watch, CVE.org

    What is affected, what to do

    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 use a specially crafted script to break out of the isolated environment and execute arbitrary code on the host system.

    The vulnerability is being actively exploited; treat it as a priority. The available sources name no fixed version. Check the vendor guidance in the references below. Immediate actions, mitigation and detection rules are in the runbook below.

    Conflicting version data — version display is hidden until the data is resolved.

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    9.5

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: Vendor (CNA), CVSS v4

    9.0

    CVSS v3

    Severity Critical on the scale from 0 to 10.

    Source: pwn.watch, CVE.org

    1.7 %

    EPSS score

    Moderate — model estimates 1-10% exploitation likelihood.

    Source: FIRST EPSS, percentile 76.9

    Show all metrics
    Severity
    Critical
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    218.67 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    actively exploitedSource: VulnCheck KEV (opens in a new tab) How we classify
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    9.5 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    9.0
    CVSS v4

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    9.5
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    1.7 %
    Moderate — model estimates 1-10% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    76.9
    High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    Actively exploited
    Published
    In CISA KEV since

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-94

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This flaw lets an attacker escape the isolated scripting environment and run code on the host. It is network-reachable without authentication or user interaction, and its impact extends beyond the vulnerable component. High attack complexity tempers the mass-exploitation risk somewhat. Exploitation likelihood is notable rather than top-tier, and CISA lists no known ransomware use. Typical targets are on-premises video-conferencing deployments in government, industrial and critical-infrastructure-adjacent organisations that run TrueConf as a sovereign alternative to cloud services. If 4307/TCP is internet-reachable, treat this as critical and patch or isolate within 24 hours. Internal-only exposure warrants high priority in the next emergency maintenance window.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Inventory: Locate every TrueConf Server instance and record the exact build. Affected versions are 5.3.x through 5.3.9 (incl. 5.3.9.10013/10015), 5.4.x through 5.4.9 (up to 5.4.9.10072), 5.5.x through 5.5.5 (up to 5.5.5.10010), and anything older.
      • Close port 4307/TCP now: Block inbound 4307/TCP from the internet and from untrusted segments at both the perimeter and host firewall until patched. Allow only allowlisted source IPs where business-critical.
      • Apply the vendor fix: A patch is available from the vendor — look up the fixed version in the TrueConf advisory. Before rollout, confirm the target build falls outside the affected ranges above.
      • Compromise assessment before patching: If 4307/TCP was internet-facing, treat the host as potentially compromised. Capture memory or EDR triage data and review processes, services and autoruns before rebooting or upgrading.
      • Rotate secrets: If a sandbox escape is suspected, rotate every credential stored on or used by the host. This includes service accounts, LDAP/AD bind accounts, database credentials, TLS private keys and TrueConf web-admin accounts.

    2. Runbook step 2

      Mitigation layers

      • Network segmentation: Place TrueConf Server in a dedicated DMZ or VLAN. Enforce default-deny egress so the server can only reach required destinations, which disrupts reverse shells and second-stage downloads.
      • Access control on 4307/TCP: Expose the port only via VPN or ZTNA or to defined client subnets. Validate whether 4307/TCP genuinely needs external reachability, and assess media ports separately.
      • IPS/NDR: Build a rule or anomaly alert for 4307/TCP that fires on unknown sources, unusually large payloads, or script-like content in the stream (shell keywords such as cmd.exe, /bin/sh, powershell). Enable vendor IPS signatures for CVE-2026-72530 as they ship.
      • Endpoint hardening: Run the TrueConf service with least privilege, not as LocalSystem or root, where the vendor supports it. Use EDR, AppLocker/WDAC or AppArmor/SELinux policy to stop the server process from spawning shells and interpreters.
      • IAM/least privilege: Use a read-only AD bind account. Minimise local admins on the host and enforce administration from a dedicated admin workstation.

    3. Runbook step 3

      Detection rules

      • Process ancestry (Sysmon EID 1 / Windows Event ID 4688): Watch for cmd.exe, powershell.exe, rundll32.exe, certutil.exe or whoami.exe spawned by the TrueConf server process. Verify the process and service name against your own inventory. KQL sketch: DeviceProcessEvents | where InitiatingProcessFileName has "trueconf" and FileName in~ ("cmd.exe","powershell.exe","rundll32.exe","certutil.exe")
      • Linux (auditd): Look for execve events whose parent is the TrueConf process and whose exe is /bin/sh, /bin/bash, curl, wget or python*. Sigma shape: logsource: linux/auditd; selection: type=EXECVE, parent=trueconf*, exe|endswith: ['/sh','/bash','/curl','/wget']
      • Network (Zeek/Suricata): Flag conn.log entries with id.resp_p == 4307 from external or previously unseen sources. Also flag new outbound connections from the server to internet hosts shortly after inbound 4307 sessions. SPL: index=zeek sourcetype=conn id.resp_p=4307 NOT src_ip IN (allowlist) | stats count by src_ip
      • File system/persistence (Sysmon EID 11, 13 / Windows Event ID 7045, 4698): Look for new executables or scripts in the TrueConf install or temp directories, new services or scheduled tasks, and new cron jobs or systemd units on Linux that coincide with 4307 traffic.

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    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 use a specially crafted script to break out of the isolated environment and execute arbitrary code on the host system.

    Source: pwn.watch, CISA KEV Catalog, cvelistv5, NVD (NIST)

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    TrueConfTrueConf Server
    • 5.3 – < 5.3.9
    • < 5.3
    • 5.5 – < 5.5.5
    • 5.4 – < 5.4.9
    • 5.3.9
    • 5.3
    • 5.5.5
    • 5.4.9
    trueconftrueconf_server
    • < 5.3.9.10015
    • < 5.3.9.10013
    • 5.4.0.12689 – < 5.4.9.10072
    • 5.4.0.12700 – < 5.4.9.10019
    • 5.5.0.13828 – < 5.5.5.10009
    • 5.5.0.13826 – < 5.5.5.10010
    • 5.3.9.10015
    • 5.3.9.10013
    • 5.4.9.10072
    • 5.4.9.10019
    • 5.5.5.10009
    • 5.5.5.10010

    Vendors and products

    Weakness classes (CWE)

    • CWE-94Improper Control of Generation of Code ('Code Injection')

      Base

      The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.

      Entry at MITRE CWE-94

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    CISA KEV CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited
    PoC-in-GitHub (nomi-sec)CVE-2026-72530-TrueConf-Sandbox-Escape- (opens in a new tab)github.comPoC (publicly reported)reported, not verified

    References & sources

    • ics-cert.kaspersky.comKLCERT-26-058: TrueConf Server. Break out of the isolated environmentThird-party advisory
    • securelist.comtr/head-mare-targets-trueconf-server-with-phantomcore/120988related
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2026-72530government-resource
    • pwn.watchpwn.watch: TrueConf Server: TrueConf Server Code Injection Vulnerabilitypwn-watch
    • trueconf.comTrueConf Server — CVE-2026-72530pwn-watch
    • NVD (NIST)NVD: CVE-2026-72530pwn-watch
    • NVD (NIST)NVD: CVE-2026-72529pwn-watch
    • cisa.govCISA Known Exploited Vulnerabilities Catalogpwn-watch

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    1. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: active, automatable: no

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      SSVC assessmentchanged
      {"id":"CVE-2026-72530","role":"CISA Coordinator","options":[{"exploitation":"active"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-08-20T17:44:03.741756Z"}
      {"id":"CVE-2026-72530","role":"CISA Coordinator","options":[{"exploitation":"active"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-08-19T00:00:00+00:00"}

      Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

    2. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: none known, automatable: no

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      SSVC assessmentchanged
      {"id":"CVE-2026-72530","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-08-19T17:16:25.283210Z"}
      {"id":"CVE-2026-72530","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-08-19T00:00:00+00:00"}

      Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

    3. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: none known, automatable: no

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://securelist.com/tr/head-mare-targets-trueconf-server-with-phantomcore/120988/
      SSVC assessmentadded
      —
      {"id":"CVE-2026-72530","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-08-19T17:16:25.283210Z"}

      Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

    4. Receivedkaspersky.com

      CVSS V4.0: AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

      CVSS V3.1: AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

      Weakness type: CWE-94

      Description added or changed

      Show 6 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      TrueConf Server
      Descriptionadded
      —
      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 use a specially crafted script to break out of the isolated environment and execute arbitrary code on the host system.
      CVSSadded
      —
      AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/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
      CVSSadded
      —
      AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
      Weakness type (CWE)added
      —
      CWE-94
      Referenceadded
      —
      https://ics-cert.kaspersky.com/advisories/2026/08/11/trueconf-server-breakout-from-isolated-environment/

      Source identifier: vulnerability@kaspersky.com

    Linked advisories

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