High
Memory corruption exploit reference
CVE-2025-6021 — Libxml2: integer overflow in xmlbuildqname() leads to stack buffer overflow in libxml2
A flaw was found in libxml2's xmlBuildQName function, where integer overflows in buffer size calculations can lead to a stack-based buffer overflow. This issue can result in memory corruption or a denial of service when processing crafted input.
25
Moderate
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
No exploitation signal in the sources consulted so far.
How the score was calculated
- EPSS 1.4% (30-day exploitation probability)+11
- Technical severity (high)+6
- CISA SSVC: exploitation "poc"+5
- Automatable exploitation (SSVC)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
1.37%
ahead of 71% of scored CVEs · Oct 14, 2026
Affects
Red Hat
Enterprise Linux and 45 more
CVSS base
7.5
High · 3 source(s)
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Exploitation
Proof of concept
none · proof-of-concept · active
Automatable
Yes
can an attacker script the kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Red Hat Enterprise Linux, Red Hat Enterprise Linux Eus, Red Hat Enterprise Linux For Arm 64…).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Red Hat | Enterprise Linux | version 9.0version 8.0version 10.0 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux Eus | version 8.4version 8.6version 8.8version 9.4version 9.6version 10.0 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux For Arm 64 | version 8.0_aarch64version 9.0_aarch64version 9.4_aarch64version 10.0_aarch64 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux For Arm 64 Eus | version 9.4_aarch64version 10.0_aarch64version 9.6_aarch64 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux For Ibm Z Systems | version 8.0_s390xversion 9.4_s390xversion 10.0_s390x | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux For Ibm Z Systems Eus | version 9.0_s390xversion 9.4_s390xversion 9.6_s390xversion 10.0_s390x | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux For Power Little Endian | version 10.0_ppc64leversion 9.0_ppc64leversion 8.0_ppc64le | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux For Power Little Endian Eus | version 9.6_ppc64leversion 10.0_ppc64leversion 9.4_ppc64le | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux Server | version 7.0 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux Server Aus | version 9.4version 9.6version 9.2version 8.6version 8.4version 8.2 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux Server For Power Little Endian Update Services For Sap Solutions | version 9.4_ppc64le | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Enterprise Linux Server Tus | version 8.8 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Hardened Images | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | In-vehicle Operating System | version 1.0 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Jboss Core Services | versions not specified by the source | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Openshift Container Platform | version 4.12version 4.18version 4.17version 4.16version 4.15version 4.14version 4.13 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Openshift Container Platform For Arm64 | version 4.17version 4.18version 4.15version 4.14version 4.13version 4.16 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Openshift Container Platform For Ibm Z | version 4.13version 4.14version 4.15version 4.16version 4.17version 4.18 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Openshift Container Platform For Linuxone | version 4.14version 4.18version 4.17version 4.16version 4.15version 4.13 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Openshift Container Platform For Power | version 4.16version 4.18version 4.17version 4.15version 4.14version 4.13 | Vulnerable | NIST National Vulnerability Database |
| Red Hat | Red Hat Discovery 2 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 10 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 7 Extended Lifecycle Support | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 8 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 8.2 Advanced Update Support | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 8.6 Telecommunications Update Service | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 8.8 Telecommunications Update Service | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 9 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Enterprise Linux 9.4 Extended Update Support | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat Insights proxy 1.5 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift Container Platform 4.12 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift Container Platform 4.13 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift Container Platform 4.14 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift Container Platform 4.15 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift Container Platform 4.16 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift Container Platform 4.17 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift Container Platform 4.18 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Red Hat | Red Hat OpenShift Container Platform 4.19 | versions not specified by the source | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Xmlsoft | Libxml2 | < 2.14.4 | Vulnerable | NIST National Vulnerability Database |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 7.5 | CVSS 3.1 | High | 3.9 | 3.6 | secalert@redhat.com via NIST National Vulnerability Database |
| 7.5 | CVSS 3.1 | High | — | — | GitHub, Inc. via GitHub Security Advisories |
| 7.5 | CVSS 3.1 | High | — | — | redhat via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (score shown at the top: secalert@redhat.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
EPSS over time FIRST
Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 1.37%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
- Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · red hat/red hat enterprise linux 10, red hat/red hat enterprise linux 7 extended lifecycle support, red hat/red hat ente
- SSVC assessment updated
- Record published
- CVSS changed · 7.5
- Source status changed · → Modified
- Record created in this database
- 2025
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× References added · Oct 13, 2026 – Oct 13, 2026
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
30 on the record
- gitlab.gnome.org/GNOME/libxml2/-/issues/926
- access.redhat.com/errata/RHSA-2025:12241
- access.redhat.com/errata/RHSA-2025:13267
- access.redhat.com/errata/RHSA-2025:14059
- access.redhat.com/errata/RHSA-2025:19020
- access.redhat.com/errata/RHSA-2026:7519
- access.redhat.com/errata/RHSA-2025:10699
- access.redhat.com/errata/RHSA-2025:12199
- access.redhat.com/errata/RHSA-2025:12237
- access.redhat.com/errata/RHSA-2025:12239
- bugzilla.redhat.com/show_bug.cgi
- access.redhat.com/security/cve/CVE-2025-6021
- access.redhat.com/errata/RHSA-2025:12099
- github.com/advisories/GHSA-32vr-5hxf-x93f
- lists.debian.org/debian-lts-announce/2025/07/msg00014.html
- nvd.nist.gov/vuln/detail/CVE-2025-6021
- access.redhat.com/errata/RHSA-2025:14396
- access.redhat.com/errata/RHSA-2025:15308
- access.redhat.com/errata/RHSA-2025:11673
- access.redhat.com/errata/RHSA-2025:10630
- access.redhat.com/errata/RHSA-2025:12240
- access.redhat.com/errata/RHSA-2025:15672
- access.redhat.com/errata/RHSA-2025:13336
- access.redhat.com/errata/RHSA-2025:13335
- cert-portal.siemens.com/productcert/html/ssa-032379.html
- access.redhat.com/errata/RHSA-2025:10698
- access.redhat.com/errata/RHSA-2025:13289
- access.redhat.com/errata/RHSA-2025:12098
- access.redhat.com/errata/RHSA-2025:11580
- access.redhat.com/errata/RHSA-2025:13325
Elsewhere on this site
Related CVEs (same products)
- Medium CVE-2026-104046 Sssd: sssd: denial of service via incomplete identity provider authentication requests 9d
- Medium CVE-2026-104045 Sssd: sssd: denial of service via race condition in autofs responder 9d
- Medium CVE-2026-104047 Sssd: sssd: information disclosure via query injection in entra id lookups 9d
- High CVE-2026-104048 Sssd: sssd: authorization bypass via cross-domain username collision in hbac evaluation 9d
- High CVE-2026-102558 Libsoup: libsoup: heap buffer overflow during websocket receive-buffer growth 16d
- High CVE-2026-102555 Libsoup: libsoup: heap buffer overflow via uninitialized length in data-uri base64 decoding 16d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No fixed version, patch or mitigation documented.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2025-6021 is "Libxml2: integer overflow in xmlbuildqname() leads to stack buffer overflow in libxml2", rated High. It affects Enterprise Linux (Red Hat); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.5 describes technical severity. EPSS 1.37% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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