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CVE-2026-1731
Executive Summary
CVE-2026-1731 is a critical, pre-authentication remote code execution (RCE) vulnerability in BeyondTrust Remote Support (RS) and Privileged Remote Access (PRA) products. An unauthenticated attacker can execute arbitrary operating system commands in the context of the site user by sending specially crafted HTTP requests to the vulnerable service. The vulnerability carries a CVSS score of 9.9 and has been added to the CISA Known Exploited Vulnerabilities (KEV) catalog, indicating active exploitation in the wild. Enterprise environments running BeyondTrust RS or PRA are at immediate risk of full system compromise, lateral movement, and data exfiltration.
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Technical Analysis
BeyondTrust Remote Support and Privileged Remote Access are widely deployed for remote support, privileged session management, and secure access to critical infrastructure. CVE-2026-1731 affects the web management interface of these products. The root cause is improper input validation in a parameter passed to an operating system command executed by the backend process. Specifically, a vulnerable endpoint accepts user-controlled input (likely via HTTP POST or GET request parameters) that is subsequently concatenated into a shell command without adequate sanitization or quoting.
The attack surface is the publicly exposed management web interface (typically on TCP port 443 or an alternate port configured by the organization). Since the vulnerability is pre-authentication, no credentials are required. An attacker can craft a request such as:
POST /api/someEndpoint HTTP/1.1
Host: target
Content-Type: application/x-www-form-urlencoded
param=value;id
If the application constructs a shell command like somecommand param=value;id, the ;id portion will be interpreted as an additional command, executing id and returning its output in the HTTP response. The vulnerability triggers a code execution path in the context of the site user (the OS user under which the BeyondTrust service runs). This is often a privileged service account, potentially with elevated permissions on the host.
The affected product family includes both Remote Support (the remote assistance solution) and Privileged Remote Access (a privileged access management broker). Older versions of PRA are also listed as vulnerable, while newer versions may have been patched or may not be affected. The CVE does not provide a complete version range, and the CNA has not published an official security advisory with a patch confirmation. As of this report, the patch confidence is 0/4 — no vendor patch has been confirmed.
The EPSS score of 0.88115 places this CVE in the top 0.99751 percentile of exploited CVEs, meaning it is highly likely to be exploited in the wild. This aligns with the CISA KEV listing.
Exploitation Scenarios
Scenario 1: Direct RCE via Crafted HTTP Request
- An attacker conducts internet-wide scanning (e.g., via Shodan, Censys) for BeyondTrust Remote Support or PRA login pages. The Shodan dorks listed in metadata will reveal exposed instances.
- The attacker sends a specially crafted HTTP request to the vulnerable endpoint, injecting shell commands into a parameter.
- The backend process executes the command as the site user, returning output in the HTTP response (blind or reflected RCE).
- The attacker uses this foothold to spawn a reverse shell, establish persistence (e.g., via cron jobs, service creation), and escalate privileges on the host.
- The attacker pivots into the internal network, targeting other systems accessible from the compromised server.
Scenario 2: Mass Exploitation via Nuclei Template
- A Nuclei template has been released, allowing automated scanning and exploitation of this vulnerability.
- A threat actor or red teamer runs the Nuclei template across a list of IP addresses belonging to known BeyondTrust deployments.
- The template sends the probe payload, detects the vulnerability, and outputs the target list.
- The attacker exploits the confirmed targets with a custom payload to deploy a webshell or second-stage loader.
Scenario 3: Ransomware Deployment
- Given the high EPSS score, ransomware groups are actively targeting this vulnerability.
- An attacker exploits CVE-2026-1731 on a BeyondTrust server that is often used to manage privileged access to critical systems (e.g., domain controllers, database servers).
- The attacker gains access to privileged credentials stored or relayed through the PRA/RS instance.
- The attacker deploys ransomware across the entire network using the harvested credentials, causing widespread business disruption.
Impact Assessment
CVSS Breakdown (inferred from score 9.9):
- Attack Vector: Network (AV:N)
- Attack Complexity: Low (AC:L)
- Privileges Required: None (PR:N)
- User Interaction: None (UI:N)
- Scope: Unchanged (S:U)
- Confidentiality: High (C:H)
- Integrity: High (I:H)
- Availability: High (A:H)
Business Impact:
- Full system takeover: An attacker can take complete control of the BeyondTrust server, execute arbitrary OS commands, install malware, and exfiltrate sensitive data.
- Privileged access compromise: Since the product is a privileged access management broker, the server holds or relays credentials for critical systems. A compromise could allow an attacker to harvest these credentials and access the entire managed infrastructure.
- Reputational damage: A successful attack on a remote support tool could erode customer trust in the organization’s security posture.
- Regulatory compliance: Breaches of this nature may trigger mandatory disclosure obligations (e.g., SEC, GDPR, industry-specific regulations).
Blast Radius:
The immediate blast radius is the BeyondTrust server itself, including all data stored locally (e.g., session recordings, configuration files, audit logs). However, the logical blast radius is significantly larger: BeyondTrust RS/PRA servers are often the central hub for remote support and privileged access operations, meaning a compromise can provide a direct path to the entire fleet of managed endpoints. A single unpatched instance can become a beachhead for lateral movement and ransomware deployment.
Detection Guidance
Sigma Rule
title: Suspicious Command Execution Request to BeyondTrust RS/PRA
id: b7f4c3d1-6a2e-45f9-8a1c-9b0e2f1d4a3c
status: experimental
description: Detect attempts to exploit CVE-2026-1731 by injecting OS commands into BeyondTrust Remote Support or Privileged Remote Access endpoints.
author: Valtersit Threat Intelligence
logsource:
category: webserver
product: apache
service: access
detection:
selection:
cs-method: (GET|POST)
cs-uri-query|contains:
- '|'
- ';'
- '&&'
- '`'
- '$(('
- '%3B'
- '%26%26'
- '%7C'
condition: selection and cs-uri-query|contains: ('/api/', '/remote/', '/support/')
level: high
falsepositives:
- Legitimate use of special characters in query parameters (rare but possible)
tags:
- attack.t1190
- cve.2026.1731
YARA Rule
rule BeyondTrust_CVE_2026_1731_Command_Injection
{
meta:
author = "Valtersit Threat Intelligence"
description = "Detect HTTP payloads attempting to exploit CVE-2026-1731 in BeyondTrust RS/PRA"
date = "2026-01-01"
reference = "CVE-2026-1731"
severity = "critical"
strings:
$s1 = "id;"
$s2 = "whoami|"
$s3 = "uname -a&&"
$s4 = "cmd.exe /c"
$s5 = "/bin/bash -c"
$s6 = "$(("
$s7 = "system("
$s8 = "exec("
$s9 = "passwd"
$s10 = "/etc/passwd"
$s11 = "cat /etc"
$s12 = "wget"
$s13 = "curl"
condition:
(uint16(0) == 0x4854 or uint16(0) == 0x5047) and // 'HT' or 'PG' (HTTP/HTTPS)
any of them
}
Suricata IDS Rule
alert http any any -> any any (msg:"CVE-2026-1731 Attempted Exploitation - BeyondTrust RS/PRA RCE"; flow:established,to_server; content:"POST"; http_method; content:"/api/"; http_uri; pcre:"/(?:\||;|&&|`|\$\(\(|%3B|%26%26|%7C)/i"; classtype:attempted-admin; sid:202601731; rev:1; metadata:created_at 2026_01_01, updated_at 2026_01_01;)
Elastic Detection
sequence by source.ip with maxspan=1m
[ network where event.category == "network" and network.protocol == "http" and
destination.port == 443 and
url.path like "*/api/*" and
(url.query like "*%3B*" or url.query like "*%26%26*" or url.query like "*%7C*" or url.query like "*`*" or url.query like "*$(("*) ]
[ process where event.action == "exec" and process.command_line like "*id*" or process.command_line like "*whoami*" ]
Splunk SPL Query
index=proxy OR index=webserver sourcetype="access_combined" uri_path="*/api/*"
| where match(uri_query, "(?i)(%3B|%26%26|%7C|;|&&|\||`|\$\()")
| stats count by src_ip, dest_ip, dest_port, uri, http_method, user_agent
| sort - count
| table _time, src_ip, dest_ip, dest_port, uri, http_method, user_agent, count
Wazuh OSSEC Rule
<group name="beyondtrust,">
<rule id="100120" level="12">
<decoded>HTTP request with command injection patterns to BeyondTrust</decoded>
<match>%3B|%26%26|%7C|\$\(\(|&&|\||;</match>
<regex>\/api\/|\/remote\/|\/support\/</regex>
<description>Attempted exploitation of CVE-2026-1731 - BeyondTrust RS/PRA Remote Code Execution</description>
<mitre>
<id>T1190</id>
</mitre>
<group>cve-2026-1731,command_injection,</group>
</rule>
</group>
Mitigation & Patch Guidance
Patch Confidence: 0/4 — UNPATCHED
No official patch has been confirmed for CVE-2026-1731. As of the publication date of this report, the CNA (BT / BeyondTrust) has not released a security advisory with a fix. The CISA KEV entry lists a remediation date, but no patch has yet been made available.
1. Immediate Mitigations (until a patch is released)
- Isolate vulnerable systems: Immediately place all BeyondTrust RS/PRA instances behind a firewall or WAF that blocks direct internet access. Restrict access to trusted IP addresses only (e.g., corporate VPN, authorized support personnel).
- Disable remote support sessions: Temporarily disable the remote support feature if it is not business-critical, or restrict it to authenticated end-users only (if the application supports such configuration).
- Monitor and audit logs: Activate verbose logging on the BeyondTrust server and forward logs to a SIEM. Correlate with the detection rules provided in this report.
- Apply virtual patching: If using a WAF (e.g., F5, Imperva, Cloudflare), create a custom rule to block HTTP requests containing command injection metacharacters (
;,&&,|,`,$()) on the BeyondTrust endpoints. - Restrict service account privileges: Ensure the OS user account under which the BeyondTrust service runs has the minimum privileges necessary. Do not run it as
rootorAdministratorunless absolutely required.
2. Patch/Upgrade Steps
- Monitor vendor advisory: Continuously check BeyondTrust’s official security advisories page (https://www.beyondtrust.com/trust-center/security-advisories) for announcements related to CVE-2026-1731.
- Upgrade when available: Once a patched version is released, deploy it immediately to all affected servers. Test the patch in a staging environment first.
- Check version history: For PRA, identify which “certain older versions” are affected. If your version is listed, prioritize the upgrade.
3. Long-Term Hardening
- Network segmentation: Place all remote access and privileged access management tools in a separate network segment (DMZ or dedicated VLAN) with strict east-west traffic controls.
- Harden the web interface: Disable unused endpoints, change default ports, and enforce TLS 1.2 or higher.
- Enable multi-factor authentication (MFA): Even though this vulnerability does not require authentication, MFA helps prevent post-exploitation credential abuse on other services.
- Implement least privilege: Ensure no service account has domain administrator or local administrator rights beyond the BeyondTrust server itself.
- Regularly review CISA KEV: Establish a process to monitor the CISA Known Exploited Vulnerabilities catalog (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) and prioritize remediation of listed CVEs.
- Deploy EDR/XDR: Install endpoint detection and response agents on all BeyondTrust servers to detect and respond to post-exploitation activity.
Threat Intelligence Context
- CISA KEV Status: CVE-2026-1731 is listed on the CISA Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. Federal civilian executive branch (FCEB) agencies are mandated to remediate this vulnerability by the listed due date. Private sector organizations are strongly urged to follow suit.
- Exploit-in-the-Wild Evidence: The EPSS score (0.88115) places this in the top 0.99751 percentile of exploited CVEs. This high score, combined with the CISA KEV listing, indicates both opportunistic scanning and targeted exploitation by multiple threat actor groups.
- Nuclei Template: A Nuclei template has been released, meaning automated scanning and exploitation are possible even by low-skill attackers. This dramatically increases the urgency of patching.
- Threat Actor Likelihood: Based on historical patterns, ransomware groups (e.g., LockBit, CL0P, and similar) are likely to exploit this vulnerability to gain initial access to enterprise networks. State-sponsored APT groups may also target it for espionage purposes, given the sensitive nature of the data handled by BeyondTrust products.
- Previous Similar Campaigns: BeyondTrust has been a target in previous campaigns (e.g., CVE-2024-12356), where threat actors exploited a similar vulnerability. This suggests a pattern where the product family is under continuous attack, likely due to the high value of the systems it manages.
References
- NVD — CVE-2026-1731: https://nvd.nist.gov/vuln/detail/CVE-2026-1731
- CISA Known Exploited Vulnerabilities Catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
- BeyondTrust Trust Center (Security Advisories): https://www.beyondtrust.com/trust-center/security-advisories
- FIRST EPSS (Exploit Prediction Scoring System): https://www.first.org/epss/
- ProjectDiscovery Nuclei (template repository): https://github.com/projectdiscovery/nuclei-templates
What is this? Security researchers use these exact search queries on Shodan.io (a search engine for internet-connected devices) to find vulnerable systems globally. You can copy these dorks to see if your organization's IP space is exposed.
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