[NEW] [high] ClamAV: Multiple vulnerabilities allow Denial of Service and disclosure of information

highCVE-2026-20337 CVE-2026-20338 CVE-2026-20339 CVE-2026-20345 CVE-2026-20346 CVE-2026-20347

A remote, anonymous attacker can exploit multiple vulnerabilities in ClamAV to perform a Denial of Service attack and disclose information.

CSIRTS triage

vendor: ClamAV product: ClamAV Denial of service Information disclosure

What: Multiple vulnerabilities allow remote attackers to conduct denial of service and disclose information in ClamAV.
Who is affected: All ClamAV deployments, including email gateways and mail servers using ClamAV, are exposed to remote attack.
Urgency: High severity with remote exploitability and multiple CVEs; commonly deployed in critical infrastructure.
Action: Update ClamAV to patched version and verify virus definitions are current after patching.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: CERT-Bund (BSI) Security Advisories (DE · national-cert · site)
Severity: high
Published: 2026-08-11
Exploitation: Not in CISA KEV at last sync
Language: Machine-translated to English — verify against the original

Original advisory: https://wid.cert-bund.de/portal/wid/securityadvisory?name=WID-SEC-2026-2708

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-203370.36% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 29% of all EPSS-scored CVEs.
Low exploitation riskCVE-2026-203380.33% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 26% of all EPSS-scored CVEs.
Low exploitation riskCVE-2026-203390.33% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 26% of all EPSS-scored CVEs.
Low exploitation riskCVE-2026-203450.33% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 26% of all EPSS-scored CVEs.
Low exploitation riskCVE-2026-203460.33% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 26% of all EPSS-scored CVEs.
Low exploitation riskCVE-2026-203470.33% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 26% of all EPSS-scored CVEs.
Low exploitation riskCVE-2026-203480.33% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 26% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-20337	coverage & exploitation status	NVD · CVE.org
CVE-2026-20338	coverage & exploitation status	NVD · CVE.org
CVE-2026-20339	coverage & exploitation status	NVD · CVE.org
CVE-2026-20345	coverage & exploitation status	NVD · CVE.org
CVE-2026-20346	coverage & exploitation status	NVD · CVE.org
CVE-2026-20347	coverage & exploitation status	NVD · CVE.org
CVE-2026-20348	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

Recent advisories for ClamAV

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

highClamAV Vulnerabilities Affecting Cisco Products: August 2026cisco-psirt · 2026-08-13
highCVE-2026-20339: ClamAV PESpin File Format Processing Integer Overflow Vulnerabilitymsrc · 2026-08-11
highCVE-2026-20345: ClamAV GPT File Format Processing Memory Corruption Vulnerabilitymsrc · 2026-08-11
highCVE-2026-20338: ClamAV ZIP File Format Processing Memory Corruption Vulnerabilitymsrc · 2026-08-11
highCVE-2026-20348: ClamAV XAR File Format Processing Memory Corruption Vulnerabilitymsrc · 2026-08-11
highCVE-2026-20337: ClamAV ZIP File Format Processing Memory Corruption Vulnerabilitymsrc · 2026-08-11