NVD / CVE Program· CNA cisco

CVE-2026-20243: ClamAV ALZ Archive Processing Denial of Service Vulnerability

Noroxi assessment

Priority: Monitor (action score 30/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.57% (FIRST EPSS).
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
According to CISA the attack is automatable: targets can be found by mass scanning.
Fixed version: azl3 clamav 1.5.2-3 on Azure Linux 3.0 1.5.3-1.

Low priority for now. Upgrade to azl3 clamav 1.5.2-3 on Azure Linux 3.0 1.5.3-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 7.5 · v3.1—No exploit Fix available

Published: Jul 1, 2026
Updated: Oct 25, 2026
EPSS: 0.5% · 47th percentile
CWE: CWE-120

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 30 / 40 · 7.5 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.5%

CISA SSVC decision

Exploitation: none
Automatable: yes
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · cisco: 7.5; NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
clamav	clamav	cpe:2.3:a:clamav:clamav
cisco	secure endpoint	cpe:2.3:a:cisco:secure_endpoint

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

cisco secure endpointbefore 1.27.2
cisco secure endpointbefore 1.29.0
cisco secure endpointbefore 8.6.2
clamav clamav1.4.0 and later · before 1.4.5
clamav clamav1.5.0 and later · before 1.5.3

Versions reported by the vendor

Affected version ranges reported by the assigning authority (cisco). Independent of NVD's CPE analysis and usually ahead of it.

Cisco Cisco Secure Endpoint
- 7.0.5, 6.2.19, 7.3.3, 7.2.13, 6.1.5, 6.3.1, 6.2.5, 7.3.5, 6.2.1, 7.2.7, 7.1.1, 6.3.5 … (+28)affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:12	clamav	before 1.4.6+dfsg-0+deb12u1	1.4.6+dfsg-0+deb12u1
Debian:13	clamav	from 0	—
Debian:14	clamav	before 1.4.5+dfsg-1	1.4.5+dfsg-1
openSUSE:Leap 16.0	clamav	before 1.5.3-160000.1.1	1.5.3-160000.1.1
openSUSE:Tumbleweed	clamav	before 1.5.3-1.1	1.5.3-1.1
SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS	clamav	before 1.5.3-150400.13.8.1	1.5.3-150400.13.8.1
SUSE:Linux Enterprise Module for Basesystem 15 SP7	clamav	before 1.5.3-150600.18.28.1	1.5.3-150600.18.28.1
SUSE:Linux Enterprise Server 12 SP5-LTSS	clamav	before 1.5.3-3.56.1	1.5.3-3.56.1
SUSE:Linux Enterprise Server 16.0	clamav	before 1.5.3-160000.1.1	1.5.3-160000.1.1

Same product

clamav: all records

Other highest-scoring records for the same primary product.

CVE-2023-20032On Feb 15, 2023, the following vulnerability in the ClamAV scanning library was disclosed: A vulnerability in the HFS+ partition file p
48Plan
CVE-2024-20328ClamAV VirusEvent File Processing Command Injection Vulnerability
46Plan
CVE-2017-12379ClamAV AntiVirus software versions 0.99.2 and prior contain a vulnerability that could allow an unauthenticated, remote attacker to cause a
43Plan

Published before and after this one in the same product

← EarlierCVE-2026-20216Jul 1, 2026 · ClamAV InstallShield File Format Processing Resource Exhaustion Vulnerability
30Monitor
← EarlierCVE-2026-20217Jul 1, 2026 · ClamAV PESpin File Format Processing Out-of-Bounds Memory Corruption Vulnerability
30Monitor
Later →CVE-2026-20244Jul 1, 2026 · ClamAV DMG File Processing Denial of Service Vulnerability
30Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
azl3 clamav 1.5.2-3 on Azure Linux 3.0	1.5.3-1 · CBL-Mariner Releases	Microsoft (MSRC)
debian:clamav	1.4.5+dfsg-1 · Debian:14	Package registry (OSV)
debian:clamav	1.4.6+dfsg-0+deb12u1 · Debian:12	Package registry (OSV)
opensuse:clamav	1.5.3-1.1 · openSUSE:Tumbleweed	Package registry (OSV)
suse:clamav	1.5.3-160000.1.1 · SUSE:Linux Enterprise Server 16.0	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

CVE-2026-202130 days apartClamAV PE File Format Processing Out-of-Bounds Memory Corruption Vulnerability
30Monitor
CVE-2026-202140 days apartClamAV FSG File Format Processing Out-of-Bounds Memory Corruption Vulnerability
30Monitor
CVE-2026-202150 days apartClamAV 7Zip File Format Processing Out-of-Bounds Memory Corruption Vulnerability
30Monitor
CVE-2026-202170 days apartClamAV PESpin File Format Processing Out-of-Bounds Memory Corruption Vulnerability
30Monitor
CVE-2026-202440 days apartClamAV DMG File Processing Denial of Service Vulnerability
30Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
No account or password is required.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: none
Integrity: none
Availability: high · the service can be disrupted

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: None
Integrity impact: None
Availability impact: High

Weakness class (CWE)

CWE-120 · Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd-secondary

Root cause

When data is copied, the source length is not compared with the size of the destination buffer. Excess data overwrites adjacent memory.

The bug in code

The whole CWE-120 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1char buf[256];
2memcpy(buf, pkt->data, pkt->len);

Fixed

1char buf[256];
2if (pkt->len > sizeof(buf)) {
3  return -EINVAL;
4}
5memcpy(buf, pkt->data, pkt->len);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

—

Change log

Fix✗ → ✓Sep 28, 2026, 10:46 PM UTC

For records you follow, these changes also arrive as notifications. →

References

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-clamav-88cFYyxR

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records