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ClamAV CVE-2026-20216

| EUVDEUVD-2026-41081 HIGH
Allocation of Resources Without Limits or Throttling (CWE-770)
2026-07-01 psirt@cisco.com GHSA-8fx8-2p33-gv76
Denial Of Service 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

Attacker-supplied file reaches the scanner remotely with no auth or interaction (AV:N/AC:L/PR:N/UI:N); impact is temporary scanner DoS 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

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 - 17:38 vuln.today

DescriptionCVE.org

A vulnerability in the InstallShield file format parser of ClamAV could allow an unauthenticated, remote attacker to cause a DoS condition on an affected device.

This vulnerability is due to improper handling of temporary resources during file scanning. An attacker could exploit this vulnerability by submitting a crafted InstallShield file to be scanned by ClamAV on an affected device. A successful exploit could allow the attacker to terminate the ClamAV scanning process and temporarily consume available system resources, resulting in a DoS condition on the affected software.

AnalysisAI

Denial of service in ClamAV's InstallShield file format parser allows a remote, unauthenticated attacker (per CVSS PR:N) to crash the scanning engine and temporarily exhaust system resources by submitting a specially crafted InstallShield file for scanning. The flaw stems from improper handling of temporary resources during file scanning (CWE-770), impacting availability only (C:N/I:N/A:H) with no code execution or data exposure. There is no public exploit identified at time of analysis and it is not listed in CISA KEV, but the network attack vector and low complexity make it easy to trigger anywhere ClamAV automatically scans attacker-supplied files.

Technical ContextAI

ClamAV is a widely deployed open-source antivirus engine used to scan email attachments, uploaded files, and gateway traffic; it ships with numerous format-specific parsers so it can unpack and inspect installer archives, including the InstallShield installer format. The root cause is CWE-770 (Allocation of Resources Without Limits or Throttling): the InstallShield parser mishandles temporary resources while unpacking/scanning a crafted file, allowing an attacker-controlled input to drive the scanning process to terminate and to temporarily consume available system resources (memory/CPU/disk temp space). Because the engine is frequently invoked automatically and non-interactively on untrusted input (mail scanning via clamd/clamdscan, upload scanners), the parser is exposed to attacker-supplied content by design, which is why a purely local file-format bug carries a network attack vector.

RemediationAI

Patch available per vendor advisory - upgrade to the fixed ClamAV release identified in the Cisco Security Advisory at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-clamav-88cFYyxR; the input data does not contain an exact fix version, so obtain the precise patched build from that advisory and do not rely on an assumed version number. As a compensating control until patched, consider disabling scanning of the affected file type where feasible - ClamAV allows selectively disabling archive/installer parsers (for example scanning options that turn off specific unpackers), which removes exposure to the vulnerable InstallShield code path at the cost of reduced detection coverage for installer-borne malware. Additionally, constrain resource exhaustion blast radius by tightening ClamAV limits (MaxScanSize, MaxFileSize, MaxRecursion, and per-process memory/cgroup limits) so a single crafted file cannot consume unbounded resources, and monitor/restart clamd automatically (watchdog) so a terminated scanning process is recovered quickly; the trade-off is that overly tight scan limits can cause large legitimate files to be skipped.

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Same weakness CWE-770 – Allocation of Resources Without Limits or Throttling

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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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CVE-2026-20216 vulnerability details – vuln.today
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