CVE-2021-1404 | Clam AntiVirus (ClamAV) Email Parser Denial of Service Vulnerability

A vulnerability in the PDF parsing module in Clam AntiVirus (ClamAV) Software versions 0.103.0 and 0.103.1 could allow an unauthenticated, remote attacker to cause a denial of service condition on an affected device. The vulnerability is due to improper buffer size tracking that may result in a heap buffer over-read. An attacker could exploit this vulnerability by sending a crafted PDF file to an affected device. An exploit could allow the attacker to cause the ClamAV scanning process to crash, resulting in a denial of service condition.

Published: 2021-04-08 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-1404 is rated Moderate Risk (59.9/100): CVSS High severity, with medium exploitation likelihood (EPSS 2.22%). EPSS rose +1.79% over the last day, indicating growing attacker interest. Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-1404

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.43% 2.22% +1.79%
2 2026-06-12 0.50% 0.43% -0.07%
3 2026-05-28 — 0.50% —

Full EPSS history (13 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-1404

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-1404

OS Trackers for CVE-2021-1404

vendor priority summary link
alpine high CVE-2021-1404: 1 source package rows (clamav); 9 state rows across 9 repos (3.11-main, 3.12-main, 3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 9, open 0. https://security.alpinelinux.org/vuln/CVE-2021-1404
debian not yet assigned CVE-2021-1404 not yet assigned priority: Debian including 1 source packages (clamav), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-1404
suse high CVE-2021-1404 severity important: SUSE including 34 source package names (clamav-0.103.11-150600.16.7, clamav-0.103.2-0.20.35.1, …), 121 product×package rows across 45 product lines (HPE Helion OpenStack 8, Image SLES12-SP5-SAP-Azure-LI-BYOS-Production, … (45 product lines)): Fixed 121. https://www.suse.com/security/cve/CVE-2021-1404/
ubuntu medium CVE-2021-1404 medium priority: Ubuntu including 1 source packages (clamav), 7 status rows across 7 suites (bionic, focal, groovy, hirsute, trusty, upstream, xenial): released 5, needs-triage 1, not-affected 1. https://ubuntu.com/security/CVE-2021-1404

Affected software / configurations for CVE-2021-1404

Vendor Product Version Raw CPE
clamav clamav 0.103.0 cpe:2.3:a:clamav:clamav:0.103.0:*:*:*:*:*:*:*
clamav clamav 0.103.1 cpe:2.3:a:clamav:clamav:0.103.1:*:*:*:*:*:*:*

References for CVE-2021-1404

cvelogic Threat Intelligence