CVE-2021-3518

There's a flaw in libxml2 in versions before 2.9.11. An attacker who is able to submit a crafted file to be processed by an application linked with libxml2 could trigger a use-after-free. The greatest impact from this flaw is to confidentiality, integrity, and availability.

Published: 2021-05-18 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2021-3518 is rated High Risk (69.4/100): CVSS High severity, with medium exploitation likelihood (EPSS 3.65%). Core evidence: EPSS rose +3.40% over the last day, indicating growing attacker interest. Mandatory action: High exploitation likelihood—assess exposure and prioritize 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-2021-3518

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 0.25% 3.65% +3.40%
2 2026-03-16 0.23% 0.25% +0.02%
3 2025-11-21 0.23%

Full EPSS history (27 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-3518

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.8 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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: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.
2.8 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]

Weakness enumeration for CVE-2021-3518

GitHub Security Advisory for CVE-2021-3518

GHSA-v4f8-2847-rwm7 · Severity: high · Ecosystem: rubygems — Nokogiri Implements libxml2 version vulnerable to use-after-free

OS Trackers for CVE-2021-3518

vendor priority summary link
alpine high CVE-2021-3518: 2 source package rows (libxml2, libxml2.13); 50 state rows across 10 repos (3.10-main, 3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 11, open 39. https://security.alpinelinux.org/vuln/CVE-2021-3518
debian not yet assigned CVE-2021-3518 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-2021-3518
gentoo low CVE-2021-3518: 1 GLSA(s) (202107-05), 1 atom(s) (dev-libs/libxml2); latest impact low. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-3518
redhat medium https://access.redhat.com/security/cve/CVE-2021-3518
suse medium CVE-2021-3518 severity moderate: SUSE including 423 source package names (0.1.0:libxml2-2-2.9.7-3.34.1, 0.1.75:libxml2-2-2.9.7-3.34.1, …), 653 product×package rows across 216 product lines (Container bci/bci-init, Container bci/dotnet-aspnet, … (216 product lines)): Fixed 621, Known Affected 23, Known Not Affected 9. https://www.suse.com/security/cve/CVE-2021-3518/
ubuntu medium CVE-2021-3518 medium priority: Ubuntu including 1 source packages (libxml2), 9 status rows across 9 suites (bionic, focal, groovy, hirsute, impish, jammy, trusty, upstream, xenial): released 7, not-affected 2. https://ubuntu.com/security/CVE-2021-3518

Affected software / configurations for CVE-2021-3518

Vendor Product Version Raw CPE
xmlsoft libxml2 < 2.9.11 cpe:2.3:a:xmlsoft:libxml2:*:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
redhat jboss_core_services cpe:2.3:a:redhat:jboss_core_services:-:*:*:*:*:*:*:*
redhat enterprise_linux 8.0 cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
fedoraproject fedora 34 cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
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 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 snapdrive cpe:2.3:a:netapp:snapdrive:-:*:*:*:*:windows:*:*
netapp hci_h410c_firmware cpe:2.3:o:netapp:hci_h410c_firmware:-:*:*:*:*:*:*:*
oracle communications_cloud_native_core_network_function_cloud_native_environment 1.10.0 cpe:2.3:a:oracle:communications_cloud_native_core_network_function_cloud_native_environment:1.10.0:*:*:*:*:*:*:*
oracle enterprise_manager_base_platform 13.4.0.0 cpe:2.3:a:oracle:enterprise_manager_base_platform:13.4.0.0:*:*:*:*:*:*:*
oracle enterprise_manager_base_platform 13.5.0.0 cpe:2.3:a:oracle:enterprise_manager_base_platform:13.5.0.0:*:*:*:*:*:*:*
oracle enterprise_manager_ops_center 12.4.0.0 cpe:2.3:a:oracle:enterprise_manager_ops_center:12.4.0.0:*:*:*:*:*:*:*
oracle mysql_workbench <= 8.0.26 cpe:2.3:a:oracle:mysql_workbench:*:*:*:*:*:*:*:*
oracle peoplesoft_enterprise_peopletools 8.58 cpe:2.3:a:oracle:peoplesoft_enterprise_peopletools:8.58:*:*:*:*:*:*:*
oracle real_user_experience_insight 13.4.1.0 cpe:2.3:a:oracle:real_user_experience_insight:13.4.1.0:*:*:*:*:*:*:*
oracle real_user_experience_insight 13.5.1.0 cpe:2.3:a:oracle:real_user_experience_insight:13.5.1.0:*:*:*:*:*:*:*

References for CVE-2021-3518

URL Tags
http://seclists.org/fulldisclosure/2021/Jul/54 Mailing List Third Party Advisory
http://seclists.org/fulldisclosure/2021/Jul/55 Mailing List Third Party Advisory
http://seclists.org/fulldisclosure/2021/Jul/58 Mailing List Third Party Advisory
http://seclists.org/fulldisclosure/2021/Jul/59 Mailing List Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1954242 Issue Tracking Patch Third Party Advisory
https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E
https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E
https://lists.debian.org/debian-lts-announce/2021/05/msg00008.html Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BZOMV5J4PMZAORVT64BKLV6YIZAFDGX6/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QVM4UJ3376I6ZVOYMHBNX4GY3NIV52WV/
https://security.gentoo.org/glsa/202107-05 Third Party Advisory
https://security.netapp.com/advisory/ntap-20210625-0002/ Third Party Advisory
https://support.apple.com/kb/HT212601 Third Party Advisory
https://support.apple.com/kb/HT212602 Third Party Advisory
https://support.apple.com/kb/HT212604 Third Party Advisory
https://support.apple.com/kb/HT212605 Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.html Patch Third Party Advisory
https://www.oracle.com/security-alerts/cpujul2022.html Not Applicable
https://www.oracle.com/security-alerts/cpuoct2021.html Patch Third Party Advisory
cvelogic Threat Intelligence