High Denial of service

CVE-2026-20216 — ClamAV InstallShield File Format Processing Resource Exhaustion Vulnerability

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.

Published Jul 1, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: cisco

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

Technical severity (high)+6
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

—

No EPSS score.

Affects

Cisco

Cisco Secure Endpoint and 1 more

CVSS base

7.5

High · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Cisco Cisco Secure Endpoint, ClamAV Clamav).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (denial of service), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Cisco	Cisco Secure Endpoint	version 7.4.3.20679version 8.4.5.30483version 7.5.21.21732version 8.4.4.30467version 8.4.4.30419version 8.4.3version 7.5.20version 8.4.1.30307 and 138 more version 8.4.2.30317version 8.4.1.30298version 7.5.19version 8.4.0version 8.2.4.30130version 8.2.3.30119version 7.5.17.21680version 7.5.15.21611version 8.2.1.21612version 7.4.3version 7.4.5version 7.5.1.20813version 7.5.1.20833version 7.5.3version 7.5.5version 8.0.1.21160version 8.0.1.21164version 7.5.7version 7.5.9version 7.5.11version 8.1.7.21585version 7.5.13.21586version 7.5.13.21598version 8.2.1.21650version 7.0.5version 6.2.19version 7.3.3version 7.2.13version 6.1.5version 6.3.1version 6.2.5version 7.3.5version 6.2.1version 7.2.7version 7.1.1version 6.3.5version 6.2.9version 7.3.1version 6.1.7version 7.2.11version 7.2.3version 7.1.5version 6.3.3version 7.3.9version 6.2.3version 6.1.9version 6.0.9version 7.2.5version 6.0.7version 6.3.7version 1.12.3version 1.8.0version 1.11.1version 1.12.4version 1.10.0version 1.12.0version 1.8.1version 1.10.1version 1.12.1version 1.12.6version 1.14.0version 1.10.2version 1.12.7version 1.12.2version 1.6.0version 1.9.0version 1.11.0version 1.7.0version 1.13.0version 1.8.4version 1.13.1version 1.9.1version 1.12.5version 1.13.2version 8.1.7.21512version 8.1.7version 8.1.5version 8.1.3.21242version 8.1.3version 8.1.5.21322version 8.1.7.21417version 1.14.1version 1.15.1version 1.15.2version 1.15.3version 1.15.4version 1.15.5version 1.15.6version 1.16.0version 1.16.1version 1.16.2version 1.16.3version 1.18.0version 1.18.1version 1.20.0version 1.21.0version 1.21.1version 1.21.2version 1.21.3version 1.22.0version 1.22.1version 1.22.2version 1.22.3version 1.22.4version 1.24.0version 1.24.1version 1.24.2version 1.24.3version 1.24.4version 1.26.0version 1.24.5version 1.26.1version 1.27.0version 1.15.0version 1.17.0version 1.17.1version 1.17.2version 1.19.0version 1.20.1version 1.20.2version 1.20.3version 1.20.4version 1.20.5version 1.20.6version 1.23.0version 1.23.1version 1.20.7version 1.20.8version 1.25.0version 1.25.1version 1.25.2version 1.27.1version 1.27.2version 7.3.13version 7.3.15version 7.4.1version 7.4.1.20425version 7.4.1.20439	Vulnerable	CVE Program (cve.org) e CISA ADP
Cisco	Cisco Secure Endpoint	< 1.27.2< 1.29.0< 8.6.2	Vulnerable	NIST National Vulnerability Database
ClamAV	Clamav	< 1.4.5≥ 1.5.0 and < 1.5.3	Vulnerable	NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
7.5	CVSS 3.1	High	3.9	3.6	psirt@cisco.com via NIST National Vulnerability Database
7.5	CVSS 3.1	High	—	—	cisco via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (score shown at the top: psirt@cisco.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-770 · Allocation of Resources Without Limits or Throttling

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Track CPU/memory spikes and availability drops correlated with request patterns.

web/proxy/WAF logsnetwork IDS/IPSresource metrics

Timeline

What happened to this CVE, newest first.

2026
Affected products added · cisco/cisco secure endpoint
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 15, 2026
CVSS changed · 7.5
Oct 15, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Jul 1, 2026 · cisco

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

1 on the record

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-clamav-88cFYyx
Vendor Advisory, NIST National Vulnerability Database

Elsewhere on this site

Cisco
every CVE for this vendor

Denial of service
same class

CWE-770
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-20348 Classic Buffer Overflow in Cisco Cisco Secure Endpoint Aug 7, 2026
High CVE-2026-20217 ClamAV PESpin File Format Processing Out-of-Bounds Memory Corruption Vulnerability Jul 1, 2026
High CVE-2026-20243 ClamAV ALZ Archive Processing Denial of Service Vulnerability Jul 1, 2026
High CVE-2026-20244 ClamAV DMG File Processing Denial of Service Vulnerability Jul 1, 2026
High CVE-2026-20213 ClamAV PE File Format Processing Out-of-Bounds Memory Corruption Vulnerability Jul 1, 2026
High CVE-2026-20214 ClamAV FSG File Format Processing Out-of-Bounds Memory Corruption Vulnerability Jul 1, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No FIRST EPSS score.
No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-20216 is "ClamAV InstallShield File Format Processing Resource Exhaustion Vulnerability", rated High. It affects Cisco Secure Endpoint (Cisco); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.5 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

Comments

Moderated technical discussion. Read the community guidelines.

No comments yet.