CVE-2021-22894
Ivanti Pulse Connect Secure Collaboration Suite Buffer Overflow Vulnerability
Description
CVE-2021-22894 is a high-severity buffer overflow vulnerability in Ivanti Pulse Connect Secure. The flaw exists in the Collaboration Suite component of Pulse Connect Secure versions before 9.1R11.4, where a remote authenticated attacker can execute arbitrary code as the root user by exploiting a maliciously crafted meeting room. CISA has added CVE-2021-22894 to its Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild under Emergency Directive 21-03. With an EPSS score of 25.73% (96.2nd percentile), this Pulse Connect Secure buffer overflow vulnerability poses a critical risk to organizations using affected VPN appliances.
KEV Information
CVSS Score
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HOpen in CalculatorCWEs
Affected Products
| Vendor | Product | Version |
|---|---|---|
| ivanti | connect secure | 9.0; 9.1 |
Multiple CVSS Assessments
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
References
- https://kb.pulsesecure.net/articles/Pulse_Security_Advisories/SA44784/?kA23Z000000boUWSAY(Broken Link, Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-22894(US Government Resource)
Weakness Type
CWE-94: Improper Control of Generation of Code ('Code Injection')
Code injection occurs when an application allows untrusted input to be incorporated into dynamically generated code. In CVE-2021-22894, the Collaboration Suite meeting room feature in Pulse Connect Secure processes user-supplied data without adequate validation, allowing an authenticated attacker to inject code that executes with root-level privileges on the server.
Learn more: CWE-94 — Improper Control of Generation of Code ('Code Injection')
CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer
Buffer overflow vulnerabilities occur when software performs operations on a memory buffer without properly restricting read or write operations to the intended boundaries. In CVE-2021-22894, the meeting room processing logic in Pulse Connect Secure fails to enforce proper memory boundaries, allowing an attacker to overwrite adjacent memory and gain control of program execution flow.
Learn more: CWE-119 — Improper Restriction of Operations within the Bounds of a Memory Buffer
Impact Analysis
CVE-2021-22894 carries a CVSS 3.1 score of 8.8 (HIGH), reflecting a severe security impact. The vulnerability is remotely exploitable over the network with low attack complexity, requiring only low-level privileges and no user interaction. Successful exploitation enables the attacker to execute arbitrary code as the root user on the Pulse Connect Secure appliance, resulting in complete compromise of confidentiality, integrity, and availability. An attacker could take full control of the VPN gateway, intercept all VPN traffic, steal user credentials, deploy persistent backdoors, or pivot into the internal corporate network. The EPSS score of 25.73% (96.2nd percentile) indicates a very high probability of exploitation, consistent with the confirmed active exploitation by advanced threat actors.
Exploit Maturity
CVE-2021-22894 is confirmed as actively exploited through its listing in the CISA Known Exploited Vulnerabilities catalog, with federal agencies required to remediate by 2022-05-03 under Emergency Directive 21-03. The EPSS score of 25.73% (96.2nd percentile) indicates near-certain exploitation activity. This vulnerability was part of a wave of Pulse Connect Secure vulnerabilities disclosed in April 2021 that were actively exploited by state-sponsored threat actors, including APT groups targeting government agencies and critical infrastructure. The combination of root-level code execution and the strategic value of VPN gateways makes this vulnerability particularly attractive to advanced adversaries.
Remediation
- Apply vendor patches immediately as required by CISA KEV directive: Apply updates per vendor instructions. Upgrade Ivanti Pulse Connect Secure to version 9.1R11.4 or later to fully address CVE-2021-22894.
- Verify that all instances of Ivanti Connect Secure versions 9.0 and 9.1 prior to 9.1R11.4 have been updated. Pay particular attention to environments where the Collaboration Suite meeting room feature is actively used.
- If immediate patching is not possible, disable the Collaboration Suite meeting room functionality to eliminate the attack vector until the update can be applied.
- Conduct a thorough forensic review using the Pulse Connect Secure Integrity Checker Tool to determine if the vulnerability was exploited prior to patching. Look for indicators of compromise such as modified system files, unauthorized accounts, or unusual network traffic patterns.
- Reset all user and administrator credentials that may have been exposed through the VPN appliance, and implement multi-factor authentication for all VPN administrator access.
Technical Details
CVE-2021-22894 exploits a combination of code injection (CWE-94) and buffer overflow (CWE-119) weaknesses in the Collaboration Suite component of Pulse Connect Secure versions before 9.1R11.4. The vulnerability resides in the meeting room processing functionality, where user-supplied input is processed without proper bounds checking, allowing an authenticated attacker to trigger a buffer overflow condition. This buffer overflow overwrites adjacent memory regions, enabling the attacker to redirect program execution and achieve arbitrary code execution with root privileges. The CVSS vector (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) indicates that while only low-level authentication is required, the resulting impact is maximum across all three security dimensions — confidentiality, integrity, and availability — with the attacker gaining complete root-level control over the appliance.
Frequently Asked Questions
Is CVE-2021-22894 being actively exploited?
Yes. CVE-2021-22894 is listed in the CISA Known Exploited Vulnerabilities catalog and is covered under Emergency Directive 21-03, confirming active exploitation by advanced threat actors. The EPSS score of 25.73% (96.2nd percentile) further confirms a very high probability of exploitation.
What products are affected by CVE-2021-22894?
CVE-2021-22894 affects Ivanti Pulse Connect Secure (formerly Pulse Secure) versions 9.0 and 9.1 prior to 9.1R11.4. The vulnerability specifically resides in the Collaboration Suite meeting room feature.
How do I fix CVE-2021-22894?
Upgrade Ivanti Pulse Connect Secure to version 9.1R11.4 or later. As an interim measure, disable the Collaboration Suite meeting room feature. Run the Pulse Connect Secure Integrity Checker Tool and reset all credentials that may have been exposed.
How severe is CVE-2021-22894?
CVE-2021-22894 has a CVSS 3.1 score of 8.8 (HIGH). Successful exploitation allows root-level code execution on the VPN appliance, enabling complete system takeover. The 96.2nd EPSS percentile ranking and confirmed active exploitation make this vulnerability an urgent priority for remediation.
Need Help With Vulnerability Management?
Our security experts can help you prioritize and remediate vulnerabilities effectively.