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ClamAV EUVDEUVD-2026-41086

| CVE-2026-20243 HIGH
Classic Buffer Overflow (CWE-120)
2026-07-01 psirt@cisco.com GHSA-v85g-hcf7-wr7c
Buffer Overflow Secure Endpoint Clamav Red Hat Suse
7.5
CVSS 3.1 · Vendor: cisco
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Severity by source

Vendor (cisco) PRIMARY
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
vuln.today AI
7.5 HIGH

ClamAV commonly scans remotely-delivered files with no auth or interaction (AV:N/AC:L/PR:N/UI:N); confirmed impact is a process crash only, so C:N/I:N/A:H.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
HIGH
qualitative
Red Hat
7.5 HIGH
qualitative

Primary rating from Vendor (cisco).

CVSS VectorVendor: cisco

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

1
Analysis Generated
Jul 01, 2026 - 17:40 vuln.today

DescriptionCVE.org

A vulnerability in the ALZ 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 ALZ 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 ALZ 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.

AnalysisAI

Denial of service in ClamAV's ALZ archive parser allows an unauthenticated, remote attacker to crash the scanning engine by submitting a crafted ALZ file, with the vendor noting possible expanded impact beyond DoS. The flaw is a heap out-of-bounds write triggered during scanning, and because ClamAV is commonly deployed as an automated mail/upload gateway scanner, an attacker only needs to get a malicious file scanned. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Craft malicious ALZ archive file
Delivery
Deliver via email or upload to scanned service
Exploit
ClamAV ALZ parser performs out-of-bounds write
Execution
Memory corruption crashes clamd process
Impact
Denial of service for scanning pipeline
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Vulnerability AssessmentAI

Exploitation The specific prerequisite is that ClamAV must be invoked to scan a file containing crafted ALZ archive content - the vulnerable code path is the ALZ format parser, so exploitation requires the target to accept and scan attacker-supplied ALZ (or ALZ-embedded) files. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The CVSS 3.1 base score is 7.5 (High) with vector AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - network-reachable, low-complexity, no privileges or user interaction, availability-only impact, which matches a reliable DoS crash of the scanning process. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker emails or uploads a specially crafted ALZ archive to a service that automatically routes files through ClamAV, such as a mail gateway or file-upload malware scanner. When clamd parses the malformed ALZ content, the out-of-bounds write corrupts memory and terminates the scanning process, disrupting scanning for all traffic. …
Remediation Patch available per vendor advisory: upgrade ClamAV to the fixed release identified in the Cisco/Talos advisory at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-clamav-88cFYyxR (the exact fixed version is not specified in the provided data - confirm the precise release from that advisory before deploying). … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

Within 24 hours: Inventory all ClamAV deployments and assess reliance on ALZ archive scanning; enable detailed logging and alerting on scanning engine crashes. …

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Threat intelligence, references, and detailed analysis are available after sign-in.

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Same weakness CWE-120 – Classic Buffer Overflow

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Vendor StatusVendor

SUSE

Severity: Important
Product Status
openSUSE Leap 16.0 Fixed
openSUSE Tumbleweed Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS Affected
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS Affected
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS Affected

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EUVD-2026-41086 vulnerability details – vuln.today
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