CVE-2021-3541

A flaw was found in libxml2. Exponential entity expansion attack its possible bypassing all existing protection mechanisms and leading to denial of service.

Published: 2021-07-09 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-3541 is rated Moderate Risk (54.5/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 1.86%). EPSS rose +1.80% 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-2021-3541

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 0.06% 1.86% +1.80%
2 2025-11-21 0.29% 0.06% -0.23%
3 2025-11-18 — 0.29% —

Full EPSS history (15 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-3541

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/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:L)
A normal user session is enough; they don’t have to be admin.
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.
 2.8 3.6 [email protected]
4.0 2.0 MEDIUM
AV:N/AC:L/Au:S/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:S)
A single authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.0 2.9 [email protected]

Weakness enumeration for CVE-2021-3541

OS Trackers for CVE-2021-3541

vendor priority summary link
alpine medium CVE-2021-3541: 3 source package rows (libxml2, libxml2.13, qt5-qtwebengine); 55 state rows across 16 repos (3.11-main, 3.12-main, 3.17-community, 3.17-main, 3.18-community, 3.18-main, 3.19-community, 3.19-main, 3.20-community, 3.20-main, 3.21-community, 3.21-main, 3.22-community, 3.22-main, edge-community, edge-main); fixed 17, open 38. https://security.alpinelinux.org/vuln/CVE-2021-3541
debian not yet assigned CVE-2021-3541 not yet assigned priority: Debian including 1 source packages (libxml2), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-3541
gentoo low CVE-2021-3541: 1 GLSA(s) (202107-05), 1 atom(s) (dev-libs/libxml2); latest impact low. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-3541
redhat medium — https://access.redhat.com/security/cve/CVE-2021-3541
suse medium CVE-2021-3541 severity moderate: SUSE including 432 source package names (0.1.0:libxml2-2-2.9.7-3.37.1, 0.1.75:libxml2-2-2.9.7-3.37.1, …), 689 product×package rows across 214 product lines (Container bci/bci-init, Container bci/dotnet-aspnet, … (214 product lines)): Fixed 661, Known Affected 19, Known Not Affected 9. https://www.suse.com/security/cve/CVE-2021-3541/
ubuntu medium CVE-2021-3541 medium priority: Ubuntu including 1 source packages (libxml2), 9 status rows across 9 suites (bionic, focal, groovy, hirsute, impish, jammy, trusty, upstream, xenial): not-affected 5, released 4. https://ubuntu.com/security/CVE-2021-3541

Affected software / configurations for CVE-2021-3541

Vendor Product Version Raw CPE
xmlsoft libxml2 < 2.9.11 cpe:2.3:a:xmlsoft:libxml2:*:*:*:*:*:*:*:*
redhat jboss_core_services — cpe:2.3:a:redhat:jboss_core_services:-:*:*:*:*:*:*:*
oracle zfs_storage_appliance_kit 8.8 cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:*
netapp active_iq_unified_manager — cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:*
netapp cloud_backup — cpe:2.3:a:netapp:cloud_backup:-:*:*:*:*:*:*:*
netapp clustered_data_ontap — cpe:2.3:a:netapp:clustered_data_ontap:-:*:*:*:*:*:*:*
netapp clustered_data_ontap_antivirus_connector — cpe:2.3:a:netapp:clustered_data_ontap_antivirus_connector:-:*:*:*:*:*:*:*
netapp manageability_software_development_kit — cpe:2.3:a:netapp:manageability_software_development_kit:-:*:*:*:*:*:*:*
netapp ontap_select_deploy_administration_utility — cpe:2.3:a:netapp:ontap_select_deploy_administration_utility:-:*:*:*:*:*:*:*
netapp smi-s_provider — cpe:2.3:a:netapp:smi-s_provider:-:*:*:*:*:*:*:*
netapp snapdrive — cpe:2.3:a:netapp:snapdrive:-:*:*:*:*:unix:*:*
netapp h410c_firmware — cpe:2.3:o:netapp:h410c_firmware:-:*:*:*:*:*:*:*
netapp h300s_firmware — cpe:2.3:o:netapp:h300s_firmware:-:*:*:*:*:*:*:*
netapp h500s_firmware — cpe:2.3:o:netapp:h500s_firmware:-:*:*:*:*:*:*:*
netapp h700s_firmware — cpe:2.3:o:netapp:h700s_firmware:-:*:*:*:*:*:*:*
netapp h300e_firmware — cpe:2.3:o:netapp:h300e_firmware:-:*:*:*:*:*:*:*
netapp h500e_firmware — cpe:2.3:o:netapp:h500e_firmware:-:*:*:*:*:*:*:*
netapp h700e_firmware — cpe:2.3:o:netapp:h700e_firmware:-:*:*:*:*:*:*:*
netapp h410s_firmware — cpe:2.3:o:netapp:h410s_firmware:-:*:*:*:*:*:*:*

References for CVE-2021-3541

cvelogic Threat Intelligence