CVE-2026-20217 in Secure Endpoint
Summary
by MITRE • 07/01/2026
A vulnerability in the PESpin file format parser of ClamAV could allow an unauthenticated, remote attacker to cause a DoS condition, or possibly other expanded impacts, resulting from memory corruption on an affected device.
This vulnerability is due to improper boundary checks for content in PESpin files during scanning, which may result in an out-of-bounds buffer write. An attacker could exploit this vulnerability by submitting a crafted file that contains PESpin content to be scanned by ClamAV on an affected device. A successful exploit could allow the attacker to cause the ClamAV scanning process to terminate, resulting in a DoS condition on the affected software.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 07/01/2026
This vulnerability resides within ClamAV's PESpin file format parser, representing a critical weakness that exposes systems to remote exploitation without authentication requirements. The flaw manifests as insufficient boundary validation mechanisms during the parsing of PESpin formatted content, creating opportunities for memory corruption attacks that can severely impact system stability and availability. Such vulnerabilities are particularly dangerous in security software environments where ClamAV operates as a primary threat detection mechanism, making this a high-impact issue for organizations relying on its protection services.
The technical implementation of this vulnerability stems from inadequate input validation procedures within the PESpin parser component of ClamAV's file format handling architecture. When processing maliciously crafted PESpin files, the software fails to properly verify buffer boundaries before writing data, leading to out-of-bounds memory operations that can trigger arbitrary code execution or process termination. This type of memory corruption vulnerability aligns with CWE-129, which specifically addresses insufficient validation of length of input buffers, and represents a classic example of how improper boundary checks in file format parsers can create exploitable conditions.
The operational impact of this vulnerability extends beyond simple denial-of-service conditions to potentially enable more sophisticated attack vectors that could compromise the entire security infrastructure. An attacker exploiting this weakness could cause ClamAV processes to crash repeatedly, effectively disabling real-time threat detection capabilities on affected systems while maintaining operational control over the scanning environment. This disruption can lead to extended periods of reduced security coverage and potential data exposure risks as malicious content may bypass detection mechanisms during the service interruption.
Organizations should implement immediate mitigations including updating ClamAV to versions that address this specific boundary checking vulnerability, implementing network segmentation to limit access to scanning systems, and deploying additional monitoring solutions to detect unusual process termination patterns. The ATT&CK framework categorizes this type of vulnerability under T1499 which covers Network Denial of Service attacks, while also aligning with T1059 for execution through command and scripting interfaces that could be leveraged post-exploitation. Security teams should also consider implementing file type filtering mechanisms to reduce exposure risk and establish incident response procedures specifically addressing this class of memory corruption vulnerabilities in anti-malware systems.
Additional protective measures include configuring ClamAV with enhanced logging capabilities to detect suspicious file processing patterns, establishing network-based intrusion detection rules targeting known PESpin format indicators, and conducting regular vulnerability assessments of security software components to identify similar boundary checking deficiencies. The remediation process should prioritize patch management procedures that ensure timely deployment of vendor security updates while maintaining system availability during update windows. Organizations must also consider implementing redundant scanning solutions to maintain threat detection capabilities during patching operations and establish baseline configurations that minimize attack surface exposure for ClamAV installations.