CVE-2025-5451: Ivanti Connect Secure Buffer Overflow Flaw

CVE-2025-5451 Overview

CVE-2025-5451 is a stack-based buffer overflow affecting Ivanti Connect Secure before version 22.7R2.8 and Ivanti Policy Secure before version 22.7R1.5. A remote authenticated attacker with administrative rights can trigger the flaw to cause a denial of service on the affected appliance. Ivanti disclosed the issue in its July 2025 security advisory covering multiple CVEs across its secure access product line. The weakness is categorized under [CWE-121: Stack-based Buffer Overflow] and [CWE-787: Out-of-bounds Write].

Critical Impact
Successful exploitation disrupts the availability of Ivanti Connect Secure and Policy Secure gateways, potentially interrupting remote access and network access control for enterprise users.

Affected Products

Ivanti Connect Secure versions prior to 22.7R2.8
Ivanti Policy Secure versions prior to 22.7R1.5
Ivanti Connect Secure 22.7 releases R1 through R2.7 and Policy Secure 22.7 releases R1 through R1.4

Discovery Timeline

2025-07-08 - CVE-2025-5451 published to the National Vulnerability Database
2025-07-08 - Ivanti releases July security advisory addressing multiple CVEs
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-5451

Vulnerability Analysis

The vulnerability resides in code paths within Ivanti Connect Secure and Ivanti Policy Secure that write attacker-influenced data to a fixed-size stack buffer without adequate bounds checking. When the affected routine processes oversized input from an authenticated administrator, the write operation extends past the allocated buffer boundary. The out-of-bounds write corrupts adjacent stack memory, including saved registers and return addresses, causing the affected process to terminate.

The impact is limited to availability. Confidentiality and integrity are not affected, and exploitation requires valid administrator credentials on the target appliance. The attack can be executed remotely over the management network interface without user interaction.

Root Cause

The root cause is missing or insufficient length validation on data copied into a stack-allocated buffer. The affected function does not enforce the destination buffer size before performing the write, meeting the criteria of [CWE-121] and [CWE-787]. Ivanti has not published the specific component or function names in its public advisory.

Attack Vector

An authenticated administrator submits a crafted request to a vulnerable management interface endpoint. The oversized payload triggers the stack overflow, corrupts stack memory, and forces the service to crash. Because the impacted service handles VPN or network access enforcement, the crash results in denial of service for downstream users relying on the gateway.

No public proof-of-concept exploit is available. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. Refer to the Ivanti July Security Advisory for vendor-supplied technical context.

Detection Methods for CVE-2025-5451

Indicators of Compromise

Unexpected process crashes, restarts, or core dumps on Ivanti Connect Secure or Policy Secure appliances
Gaps in VPN or policy enforcement logs coinciding with administrator API calls
Anomalously large request payloads directed at administrative endpoints from authenticated admin sessions

Detection Strategies

Correlate authenticated administrator activity with service restart events on the appliance
Alert on repeated 5xx responses or connection resets returned by the management interface following admin requests
Baseline the size and structure of legitimate administrative requests and flag statistical outliers

Monitoring Recommendations

Forward Ivanti appliance syslog and audit logs to a centralized analytics platform for retention and correlation
Monitor administrator account usage for logins from unexpected source addresses or outside change windows
Track availability metrics for the Connect Secure and Policy Secure services to detect denial-of-service conditions promptly

How to Mitigate CVE-2025-5451

Immediate Actions Required

Upgrade Ivanti Connect Secure to 22.7R2.8 or later
Upgrade Ivanti Policy Secure to 22.7R1.5 or later
Rotate administrator credentials and audit privileged account membership on affected appliances
Restrict access to the administrative interface to a limited management network or bastion hosts

Patch Information

Ivanti addressed CVE-2025-5451 in Connect Secure 22.7R2.8 and Policy Secure 22.7R1.5. Full remediation details and download instructions are available in the Ivanti July Security Advisory.

Workarounds

Limit administrative interface exposure to trusted management subnets using network access control lists
Enforce multi-factor authentication for all administrator accounts to reduce credential compromise risk
Apply the principle of least privilege by removing unnecessary admin accounts pending patch deployment

bash

# Example: restrict admin interface access at the network edge
# Replace 10.10.20.0/24 with your authorized management subnet
iptables -A INPUT -p tcp --dport 443 -s 10.10.20.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP