CVE-2021-46143 [High] | Integer Overflow in Libexpat

CVE-2021-46143 is rated High Exploit Risk (78.4/100): CVSS High severity, with medium exploitation likelihood (EPSS 4.08%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

EDB-ID	Source	Kind	Published	Link
—	nvd_ref	exploit_tag		Exploit-DB ↗

EDB-ID

Source

Kind

Published

Link

—

nvd_ref

exploit_tag

Exploit-DB ↗

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-08	4.19%	4.08%	-0.11%
2	2026-05-26	4.08%	4.19%	+0.11%
3	2025-12-30	—	4.08%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-08

4.19%

4.08%

-0.11%

2026-05-26

4.08%

4.19%

+0.11%

2025-12-30

—

4.08%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
8.1	3.1	HIGH	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. 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:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	2.2	5.9	[email protected]
7.8	3.1	HIGH	`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:L) They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by. 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:R) A real person has to do something—click, install, enable—otherwise it doesn’t land. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.8	5.9	[email protected]
6.8	2.0	MEDIUM	`AV:N/AC:M/Au:N/C:P/I:P/A:P` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:M) Exploitation needs some favorable conditions, but not exceptional ones. Authentication (AU:N) No authentication is required. Confidentiality impact (C:P) Partial confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:P) Partial availability impact.	8.6	6.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

8.1

3.1

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
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:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

2.2

5.9

[email protected]

7.8

3.1

HIGH

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

Attack vector (AV:L): They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
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:R): A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.8

5.9

[email protected]

6.8

2.0

MEDIUM

AV:N/AC:M/Au:N/C:P/I:P/A:P Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:M): Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:P): Partial confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:P): Partial availability impact.

8.6

6.4

[email protected]

OS Trackers for CVE-2021-46143

vendor	priority	summary	link
`alpine`	—	CVE-2021-46143: 1 source package rows (expat); 8 state rows across 8 repos (3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 8, open 0.	https://security.alpinelinux.org/vuln/CVE-2021-46143
`debian`	not yet assigned	CVE-2021-46143 not yet assigned priority: Debian including 2 source packages (expat, libxmltok), 7 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5, open 2.	https://security-tracker.debian.org/tracker/CVE-2021-46143
`gentoo`	high	CVE-2021-46143: 1 GLSA(s) (202209-24), 1 atom(s) (dev-libs/expat); latest impact high.	https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-46143
`redhat`	medium	—	https://access.redhat.com/security/cve/CVE-2021-46143
`suse`	high	CVE-2021-46143 severity important: SUSE including 325 source package names (0.1.0:libexpat1-2.2.5-3.9.1, 0.1.75:libexpat1-2.2.5-3.9.1, …), 566 product×package rows across 156 product lines (Container bci/bci-init, Container bci/golang, … (156 product lines)): Fixed 396, Known Affected 166, Known Not Affected 4.	https://www.suse.com/security/cve/CVE-2021-46143/
`ubuntu`	medium	CVE-2021-46143 medium priority: Ubuntu including 50 source packages (apache2, apr-util, …), 730 status rows across 15 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): ignored 266, DNE 187, not-affected 142, needs-triage 97, released 38.	https://ubuntu.com/security/CVE-2021-46143

Affected software / configurations for CVE-2021-46143

Vendor	Product	Version	Raw CPE
libexpat_project	libexpat	< 2.4.3	cpe:2.3:a:libexpat_project:libexpat::::::::
netapp	active_iq_unified_manager	—	cpe:2.3:a:netapp:active_iq_unified_manager:-:::::vmware_vsphere::
netapp	clustered_data_ontap	—	cpe:2.3:a:netapp:clustered_data_ontap:-:::::::*
netapp	hci_baseboard_management_controller	h610c	cpe:2.3:a:netapp:hci_baseboard_management_controller:h610c:::::::*
netapp	hci_baseboard_management_controller	h610s	cpe:2.3:a:netapp:hci_baseboard_management_controller:h610s:::::::*
netapp	hci_baseboard_management_controller	h615c	cpe:2.3:a:netapp:hci_baseboard_management_controller:h615c:::::::*
netapp	oncommand_workflow_automation	—	cpe:2.3:a:netapp:oncommand_workflow_automation:-:::::::*
netapp	solidfire_\&_hci_management_node	—	cpe:2.3:a:netapp:solidfire_\&_hci_management_node:-:::::::*
tenable	nessus	< 8.15.3	cpe:2.3:a:tenable:nessus::::::::
tenable	nessus	>= 10.0.0, < 10.1.1	cpe:2.3:a:tenable:nessus::::::::
siemens	sinema_remote_connect_server	< 3.1	cpe:2.3:a:siemens:sinema_remote_connect_server::::::::

References for CVE-2021-46143

URL	Tags
http://www.openwall.com/lists/oss-security/2022/01/17/3	Mailing List Patch Third Party Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-484086.pdf	Patch Third Party Advisory
https://github.com/libexpat/libexpat/issues/532	Exploit Issue Tracking Patch Third Party Advisory
https://github.com/libexpat/libexpat/pull/538	Patch Third Party Advisory
https://security.gentoo.org/glsa/202209-24	Third Party Advisory
https://security.netapp.com/advisory/ntap-20220121-0006/	Third Party Advisory
https://www.debian.org/security/2022/dsa-5073	Third Party Advisory
https://www.tenable.com/security/tns-2022-05	Third Party Advisory

URL

CVE-2021-46143

Public exploit references (Exploit-DB) for CVE-2021-46143

Exploit prediction scoring system (EPSS) score for CVE-2021-46143

Common vulnerability scoring system (CVSS) metrics for CVE-2021-46143

Weakness enumeration for CVE-2021-46143

OS Trackers for CVE-2021-46143

Affected software / configurations for CVE-2021-46143

References for CVE-2021-46143