CVE-2021-3517

There is a flaw in the xml entity encoding functionality of libxml2 in versions before 2.9.11. An attacker who is able to supply a crafted file to be processed by an application linked with the affected functionality of libxml2 could trigger an out-of-bounds read. The most likely impact of this flaw is to application availability, with some potential impact to confidentiality and integrity if an attacker is able to use memory information to further exploit the application.

Published: 2021-05-19 Last update: 2025-12-02 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2021-3517 is rated Moderate Risk (42/100): CVSS High severity, with low exploitation likelihood (EPSS 0.08%). Mandatory action: 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-2021-3517

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 2025-11-21 1.20% 0.08% -1.12%
2 2025-11-18 0.08% 1.20% +1.12%
3 2025-03-17 0.08%

Full EPSS history (22 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-3517

CVSS metrics for this CVE.

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:U/C:L/I:L/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:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
3.9 4.7 [email protected]
8.6 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/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:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
3.9 4.7 134c704f-9b21-4f2e-91b3-4a467353bcc0
7.5 2.0 HIGH
AV:N/AC:L/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:L)
Exploitation conditions are straightforward and predictable.
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.
10.0 6.4 [email protected]

Weakness enumeration for CVE-2021-3517

GitHub Security Advisory for CVE-2021-3517

GHSA-jw9f-hh49-cvp9 · Severity: high · Ecosystem: rubygems — Nokogiri contains libxml Out-of-bounds Write vulnerability

OS Trackers for CVE-2021-3517

vendor priority summary link
alpine CVE-2021-3517: 3 source package rows (libxml2, libxml2.13, qt5-qtwebengine); 57 state rows across 17 repos (3.10-main, 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 18, open 39. https://security.alpinelinux.org/vuln/CVE-2021-3517
debian not yet assigned CVE-2021-3517 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-2021-3517
gentoo low CVE-2021-3517: 1 GLSA(s) (202107-05), 1 atom(s) (dev-libs/libxml2); latest impact low. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-3517
redhat medium https://access.redhat.com/security/cve/CVE-2021-3517
suse high CVE-2021-3517 severity important: SUSE including 433 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, …), 663 product×package rows across 216 product lines (Container bci/bci-init, Container bci/dotnet-aspnet, … (216 product lines)): Fixed 517, Known Affected 137, Known Not Affected 9. https://www.suse.com/security/cve/CVE-2021-3517/
ubuntu medium CVE-2021-3517 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-2021-3517

Affected software / configurations for CVE-2021-3517

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:-:*:*:*:*:*:*:*
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:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
netapp active_iq_unified_manager cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:*
netapp active_iq_unified_manager cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:windows:*:*
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 e-series_santricity_os_controller >= 11.0.0, <= 11.70.1 cpe:2.3:a:netapp:e-series_santricity_os_controller:*:*:*:*:*:*:*:*
netapp e-series_santricity_storage_manager cpe:2.3:a:netapp:e-series_santricity_storage_manager:-:*:*:*:*:*:*:*
netapp e-series_santricity_web_services cpe:2.3:a:netapp:e-series_santricity_web_services:-:*:*:*:*:web_services_proxy:*:*
netapp hci_management_node cpe:2.3:a:netapp:hci_management_node:-:*:*:*:*:*:*:*
netapp manageability_software_development_kit cpe:2.3:a:netapp:manageability_software_development_kit:-:*:*:*:*:*:*:*
netapp oncommand_insight cpe:2.3:a:netapp:oncommand_insight:-:*:*:*:*:*:*:*
netapp oncommand_workflow_automation cpe:2.3:a:netapp:oncommand_workflow_automation:-:*:*:*:*:*:*:*
netapp ontap_select_deploy_administration_utility cpe:2.3:a:netapp:ontap_select_deploy_administration_utility:-:*:*:*:*:*:*:*
netapp santricity_unified_manager cpe:2.3:a:netapp:santricity_unified_manager:-:*:*:*:*:*:*:*
netapp snapdrive cpe:2.3:a:netapp:snapdrive:-:*:*:*:*:windows:*:*
netapp snapmanager cpe:2.3:a:netapp:snapmanager:-:*:*:*:*:oracle:*:*
netapp snapmanager cpe:2.3:a:netapp:snapmanager:-:*:*:*:*:sap:*:*
netapp solidfire cpe:2.3:a:netapp:solidfire:-:*:*:*:*:*:*:*
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 mysql_workbench <= 8.0.26 cpe:2.3:a:oracle:mysql_workbench:*:*:*:*:*:*:*:*
oracle openjdk 8 cpe:2.3:a:oracle:openjdk:8:update301:*:*:*:*:*:*
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:*:*:*:*:*:*:*
oracle zfs_storage_appliance_kit 8.8 cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:*

References for CVE-2021-3517

URL Tags
https://bugzilla.redhat.com/show_bug.cgi?id=1954232 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://security.netapp.com/advisory/ntap-20211022-0004/ Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.html Patch Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.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