CVE-2021-1405 | Clam AntiVirus (ClamAV) PDF Parser Denial of Service Vulnerability

A vulnerability in the email parsing module in Clam AntiVirus (ClamAV) Software version 0.103.1 and all prior versions could allow an unauthenticated, remote attacker to cause a denial of service condition on an affected device. The vulnerability is due to improper variable initialization that may result in an NULL pointer read. An attacker could exploit this vulnerability by sending a crafted email to an affected device. An exploit could allow the attacker to cause the ClamAV scanning process 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-2021-1405 is rated Moderate Risk (57.9/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.32%). 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-2021-1405

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 2026-05-28 1.49% 1.32% -0.17%
2 2026-02-20 1.42% 1.49% +0.07%
3 2025-12-28 — 1.42% —

Full EPSS history (24 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-1405

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-2021-1405

OS Trackers for CVE-2021-1405

vendor priority summary link
alpine high CVE-2021-1405: 1 source package rows (clamav); 30 state rows across 10 repos (3.10-main, 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 21. https://security.alpinelinux.org/vuln/CVE-2021-1405
debian not yet assigned CVE-2021-1405 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-2021-1405
gentoo low CVE-2021-1405: 1 GLSA(s) (202104-07), 1 atom(s) (app-antivirus/clamav); latest impact low. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-1405
suse high CVE-2021-1405 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-2021-1405/
ubuntu medium CVE-2021-1405 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-2021-1405

Affected software / configurations for CVE-2021-1405

Vendor Product Version Raw CPE
clamav clamav <= 0.103.1 cpe:2.3:a:clamav:clamav:*:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

References for CVE-2021-1405

cvelogic Threat Intelligence