CVE-2022-20770 [High] | Denial of Service in Clamav

On April 20, 2022, the following vulnerability in the ClamAV scanning library versions 0.103.5 and earlier and 0.104.2 and earlier was disclosed: A vulnerability in CHM file parser of Clam AntiVirus (ClamAV) versions 0.104.0 through 0.104.2 and LTS version 0.103.5 and prior versions could allow an unauthenticated, remote attacker to cause a denial of service condition on an affected device. For a description of this vulnerability, see the ClamAV blog. This advisory will be updated as additional information becomes available.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-03-28	0.66%	0.89%	+0.23%
2	2026-03-27	0.64%	0.66%	+0.02%
3	2026-03-22	—	0.64%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-03-28

0.66%

0.89%

+0.23%

2026-03-27

0.64%

0.66%

+0.02%

2026-03-22

—

0.64%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
8.6	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. 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	4.0	[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]
7.8	2.0	HIGH	`AV:N/AC:L/Au:N/C:N/I:N/A:C` 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:C) Complete availability impact.	10.0	6.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

8.6

3.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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:C): Breaking this can reach past the original component and bite other resources—bigger blast radius.
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

4.0

[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]

7.8

2.0

HIGH

AV:N/AC:L/Au:N/C:N/I:N/A:C 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:C): Complete availability impact.

10.0

6.9

[email protected]

OS Trackers for CVE-2022-20770

vendor	priority	summary	link
`alpine`	high	CVE-2022-20770: 1 source package rows (clamav); 26 state rows across 3 repos (3.12-main, 3.22-community, edge-community); fixed 1, open 25.	https://security.alpinelinux.org/vuln/CVE-2022-20770
`debian`	not yet assigned	CVE-2022-20770 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-2022-20770
`gentoo`	normal	CVE-2022-20770: 1 GLSA(s) (202310-01), 1 atom(s) (app-antivirus/clamav); latest impact normal.	https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2022-20770
`suse`	medium	CVE-2022-20770 severity moderate: SUSE including 31 source package names (clamav-0.103.11-150600.16.7, clamav-0.103.6-0.20.47.1, …), 54 product×package rows across 16 product lines (Image SLES12-SP5-SAP-Azure-LI-BYOS-Production, Image SLES12-SP5-SAP-Azure-VLI-BYOS-Production, … (16 product lines)): Fixed 54.	https://www.suse.com/security/cve/CVE-2022-20770/
`ubuntu`	low	CVE-2022-20770 low priority: Ubuntu including 1 source packages (clamav), 8 status rows across 8 suites (bionic, focal, impish, jammy, kinetic, trusty, upstream, xenial): released 8.	https://ubuntu.com/security/CVE-2022-20770

Affected software / configurations for CVE-2022-20770

Vendor	Product	Version	Raw CPE
clamav	clamav	<= 0.103.5	cpe:2.3:a:clamav:clamav:::::lts:::*
clamav	clamav	>= 0.104.0, <= 0.104.2	cpe:2.3:a:clamav:clamav::::::::
cisco	secure_endpoint	< 1.16.3	cpe:2.3:a:cisco:secure_endpoint::::::macos::*
cisco	secure_endpoint	< 1.17.2	cpe:2.3:a:cisco:secure_endpoint::::::linux::*
cisco	secure_endpoint	< 7.5.5	cpe:2.3:a:cisco:secure_endpoint::::::windows::*
cisco	secure_endpoint	>= 1.18.0, < 1.18.2	cpe:2.3:a:cisco:secure_endpoint::::::linux::*
cisco	secure_endpoint	>= 1.18.0, < 1.18.2	cpe:2.3:a:cisco:secure_endpoint::::::macos::*
fedoraproject	fedora	34	cpe:2.3:o:fedoraproject:fedora:34:::::::*
fedoraproject	fedora	35	cpe:2.3:o:fedoraproject:fedora:35:::::::*
fedoraproject	fedora	36	cpe:2.3:o:fedoraproject:fedora:36:::::::*
debian	debian_linux	9.0	cpe:2.3:o:debian:debian_linux:9.0:::::::*

References for CVE-2022-20770

URL	Tags
https://lists.debian.org/debian-lts-announce/2022/06/msg00004.html	Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/7RV6BLIATIJE74SQ6NG5ZC4JK5MMDQ2R/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BX5ZXNHP4NFYQ5BFSKY3WT7NTBZUYG7L/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/N4NNBIJVG6Z4PDIKUZXTYXICYUAYAZ56/
https://security.gentoo.org/glsa/202310-01
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-clamav-dos-prVGcHLd	Third Party Advisory

URL

CVE-2022-20770 | ClamAV CHM File Parsing Denial of Service Vulnerability Affecting Cisco Products: April 2022

Exploit prediction scoring system (EPSS) score for CVE-2022-20770

Common vulnerability scoring system (CVSS) metrics for CVE-2022-20770

Weakness enumeration for CVE-2022-20770

OS Trackers for CVE-2022-20770

Affected software / configurations for CVE-2022-20770

References for CVE-2022-20770