XML external entity (XXE) vulnerability in the xmlStringLenDecodeEntities function in parser.c in libxml2 before 2.9.4, when not in validati
XML external entity (XXE) vulnerability in the xmlStringLenDecodeEntities function in parser.c in libxml2 before 2.9.4, when not in validating mode, allows context-dependent attackers to read arbitrary files or cause a denial of service (resource consumption) via unspecified vectors.
- Published
- Jun 9, 2016
- Updated
- Jun 16, 2026
- EPSS
- 1.7% · 76th percentile
- CWE
- CWE-20
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Report tools
Action score
28
Monitor
Low priority for now.
- CVSS
- 28 / 40 · 7.1 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 1.7%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
| canonical | ubuntu linux | cpe:2.3:o:canonical:ubuntu_linux |
| xmlsoft | libxml2 | cpe:2.3:a:xmlsoft:libxml2 |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- canonical ubuntu linux12.04
- canonical ubuntu linux14.04
- canonical ubuntu linux15.10
- canonical ubuntu linux16.04
- debian debian linux8.0
- xmlsoft libxml2up to 2.9.3 inclusive
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | libxml2 | before 2.9.3+dfsg1-1.1 | 2.9.3+dfsg1-1.1 |
| Debian:7 | libxml2 | before 2.8.0+dfsg1-7+wheezy6 | 2.8.0+dfsg1-7+wheezy6 |
| Debian:8 | libxml2 | before 2.9.1+dfsg1-5+deb8u2 | 2.9.1+dfsg1-5+deb8u2 |
| Red Hat:enterprise_linux:6::client | libxml2 | before 0:2.7.6-21.el6_8.1 | 0:2.7.6-21.el6_8.1 |
| Red Hat:enterprise_linux:6::client | libxml2-debuginfo | before 0:2.7.6-21.el6_8.1 | 0:2.7.6-21.el6_8.1 |
| Red Hat:enterprise_linux:6::client | libxml2-devel | before 0:2.7.6-21.el6_8.1 | 0:2.7.6-21.el6_8.1 |
| Red Hat:enterprise_linux:6::client | libxml2-python | before 0:2.7.6-21.el6_8.1 | 0:2.7.6-21.el6_8.1 |
| Red Hat:enterprise_linux:6::client | libxml2-static | before 0:2.7.6-21.el6_8.1 | 0:2.7.6-21.el6_8.1 |
| Red Hat:enterprise_linux:7::client | libxml2 | before 0:2.9.1-6.el7_2.3 | 0:2.9.1-6.el7_2.3 |
| Red Hat:enterprise_linux:7::client | libxml2-debuginfo | before 0:2.9.1-6.el7_2.3 | 0:2.9.1-6.el7_2.3 |
| Red Hat:enterprise_linux:7::client | libxml2-devel | before 0:2.9.1-6.el7_2.3 | 0:2.9.1-6.el7_2.3 |
| Red Hat:enterprise_linux:7::client | libxml2-python | before 0:2.9.1-6.el7_2.3 | 0:2.9.1-6.el7_2.3 |
| Red Hat:enterprise_linux:7::client | libxml2-static | before 0:2.9.1-6.el7_2.3 | 0:2.9.1-6.el7_2.3 |
| SUSE:Linux Enterprise Desktop 12 | libxml2 | before 2.9.1-24.1 | 2.9.1-24.1 |
| SUSE:Linux Enterprise Desktop 12 | python-libxml2 | before 2.9.1-24.1 | 2.9.1-24.1 |
| SUSE:Linux Enterprise Software Development Kit 11 SP4 | libxml2 | before 2.7.6-0.44.1 | 2.7.6-0.44.1 |
| SUSE:OpenStack Cloud 5 | libxml2-python | before 2.7.6-0.44.4 | 2.7.6-0.44.4 |
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Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:libxml2 | 2.9.3+dfsg1-1.1 · Debian:12 | Package registry (OSV) |
| red hat:libxml2 | 0:2.7.6-21.el6_8.1 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:libxml2-debuginfo | 0:2.7.6-21.el6_8.1 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:libxml2-devel | 0:2.7.6-21.el6_8.1 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:libxml2-python | 0:2.7.6-21.el6_8.1 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:libxml2-static | 0:2.7.6-21.el6_8.1 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| suse:libxml2 | 2.9.1-24.1 · SUSE:Linux Enterprise Desktop 12 | Package registry (OSV) |
| suse:libxml2-python | 2.7.6-0.44.4 · SUSE:OpenStack Cloud 5 | Package registry (OSV) |
| suse:python-libxml2 | 2.9.1-24.1 · SUSE:Linux Enterprise Desktop 12 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Someone with local access to the system can trigger it.
- No account or password is required.
- A user must open a link or visit a page.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-20 · Improper Input ValidationCVSS vector
CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Buffer Overflow via Environment VariablesCAPEC-10likelihood: High · High
- Server Side Include (SSI) InjectionCAPEC-101likelihood: High · High
- Cross Zone ScriptingCAPEC-104likelihood: Medium · High
- Command Line Execution through SQL InjectionCAPEC-108likelihood: Low · Very High
- Object Relational Mapping InjectionCAPEC-109likelihood: Low · High
- SQL Injection through SOAP Parameter TamperingCAPEC-110likelihood: High · Very High
- Double EncodingCAPEC-120likelihood: Low · Medium
- Subverting Environment Variable ValuesCAPEC-13likelihood: High · Very High
ATT&CK techniques
- Obfuscated Files or InformationT1027
- Masquerading: Invalid Code SignatureT1036.001
- Steal Web Session CookieT1539
- Subvert Trust Controls: Code SigningT1553.002
- Impair Defenses:Impair Command History LoggingT1562.003
- Hijack Execution Flow:Dynamic Linker HijackingT1574.006
- Hijack Execution Flow:Path Interception by PATH Environment VariableT1574.007
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- jvn.jp/en/jp/JVN17535578/index.html
- jvndb.jvn.jp/en/contents/2017/JVNDB-2017-000066.html
- lists.apple.com/archives/security-announce/2016/Jul/msg00000.html
- lists.apple.com/archives/security-announce/2016/Jul/msg00001.html
- lists.apple.com/archives/security-announce/2016/Jul/msg00002.html
- lists.apple.com/archives/security-announce/2016/Jul/msg00003.html
- lists.apple.com/archives/security-announce/2016/Jul/msg00005.html
- rhn.redhat.com/errata/RHSA-2016-2957.html
- www.openwall.com/lists/oss-security/2016/05/25/2
- www.oracle.com/technetwork/security-advisory/cpujan2018-3236628.html
- www.oracle.com/technetwork/topics/security/bulletinjul2016-3090568.html
- www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.html
- www.securityfocus.com/bid/90865
- www.securitytracker.com/id/1036348
- www.slackware.com/security/viewer.php?l=slackware-security&y=2016&m=slackware-security.404722
- www.ubuntu.com/usn/USN-2994-1
- xmlsoft.org/news.html
- access.redhat.com/errata/RHSA-2016:1292
- git.gnome.org/browse/libxml2/commit/?id=b1d34de46a11323fccffa9fadeb33be670d602f5
- h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05194709
Vendor advisories and official records. Exploit/PoC links are deliberately left out.