expat before version 2.4.0 does not properly handle entities expansion unless an application developer uses the XML_SetEntityDeclHandler fun
expat before version 2.4.0 does not properly handle entities expansion unless an application developer uses the XML_SetEntityDeclHandler function, which allows remote attackers to cause a denial of service (resource consumption), send HTTP requests to intranet servers, or read arbitrary files via a crafted XML document, aka an XML External Entity (XXE) issue. NOTE: it could be argued that because expat already provides the ability to disable external entity expansion, the responsibility for resolving this issue lies with application developers; according to this argument, this entry should be REJECTed, and each affected application would need its own CVE.
- Published
- Jan 21, 2014
- Updated
- Jun 16, 2026
- EPSS
- 19.4% · 97th percentile
- CWE
- CWE-611
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Report tools
Action score
33
Monitor
Low priority for now.
- CVSS
- 27 / 40 · 6.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 6 / 30 · 19.4%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| libexpat project | libexpat | cpe:2.3:a:libexpat_project:libexpat |
| python | python | cpe:2.3:a:python:python |
| apple | ipados | cpe:2.3:o:apple:ipados |
| apple | iphone os | cpe:2.3:o:apple:iphone_os |
| apple | macos | cpe:2.3:o:apple:macos |
| apple | tvos | cpe:2.3:o:apple:tvos |
| apple | watchos | cpe:2.3:o:apple:watchos |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- apple ipadosbefore 14.8
- apple iphone osbefore 14.8
- apple macosbefore 11.6
- apple tvosbefore 15.0
- apple watchosbefore 8.0
- libexpat project libexpatbefore 2.4.0
- python python3.9.0 and later · before 3.9.7
- python python3.8.0 and later · before 3.8.12
- python python3.7.0 and later · before 3.7.12
- python python3.6.0 and later · before 3.6.15
Versions reported by the vendor
Affected version ranges reported by the assigning authority (redhat). Independent of NVD's CPE analysis and usually ahead of it.
github.com/libexpat/libexpat/ libexpat
- before 2.4.0affected · semver
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | expat | before 2.4.1-2 | 2.4.1-2 |
| Debian:12 | libxmltok | all versions | — |
| openSUSE:Tumbleweed | expat | before 2.4.1-1.2 | 2.4.1-1.2 |
| openSUSE:Tumbleweed | python38 | before 3.8.12-1.2 | 3.8.12-1.2 |
| Red Hat:enterprise_linux:8::baseos | expat | before 0:2.5.0-1.el8_10 | 0:2.5.0-1.el8_10 |
| Red Hat:enterprise_linux:8::baseos | expat-debuginfo | before 0:2.5.0-1.el8_10 | 0:2.5.0-1.el8_10 |
| Red Hat:enterprise_linux:8::baseos | expat-debugsource | before 0:2.5.0-1.el8_10 | 0:2.5.0-1.el8_10 |
| Red Hat:enterprise_linux:8::baseos | expat-devel | before 0:2.5.0-1.el8_10 | 0:2.5.0-1.el8_10 |
| Red Hat:enterprise_linux:9::appstream | expat-debuginfo | before 0:2.4.9-1.el9_1 | 0:2.4.9-1.el9_1 |
| Red Hat:enterprise_linux:9::appstream | expat-debugsource | before 0:2.4.9-1.el9_1 | 0:2.4.9-1.el9_1 |
| Red Hat:enterprise_linux:9::appstream | expat-devel | before 0:2.4.9-1.el9_1 | 0:2.4.9-1.el9_1 |
| Red Hat:enterprise_linux:9::baseos | expat | before 0:2.4.9-1.el9_1 | 0:2.4.9-1.el9_1 |
| Red Hat:rhel_aus:8.2::baseos | expat | before 0:2.2.10-1.el8_2 | 0:2.2.10-1.el8_2 |
| Red Hat:rhel_aus:8.4::baseos | expat | before 0:2.2.10-1.el8_4 | 0:2.2.10-1.el8_4 |
| Red Hat:rhel_aus:8.6::baseos | expat | before 0:2.2.10-1.el8_6 | 0:2.2.10-1.el8_6 |
| Red Hat:rhel_e4s:8.8::baseos | expat | before 0:2.2.10-1.el8_8 | 0:2.2.10-1.el8_8 |
| Red Hat:rhel_e4s:9.0::baseos | expat | before 0:2.2.10-12.el9_0.4 | 0:2.2.10-12.el9_0.4 |
| SUSE:Linux Micro 6.0 | expat | before 2.7.1-1.1 | 2.7.1-1.1 |
| SUSE:Linux Micro 6.1 | expat | before 2.7.1-slfo.1.1_1.1 | 2.7.1-slfo.1.1_1.1 |
Same product
libexpat project: all recordsOther highest-scoring records for the same primary product.
- CVE-2022-25236xmlparse.c in Expat (aka libexpat) before 2.4.5 allows attackers to insert namespace-separator characters into namespace URIs.50Plan
- CVE-2022-25315In Expat (aka libexpat) before 2.4.5, there is an integer overflow in storeRawNames.40Plan
- CVE-2022-25235xmltok_impl.c in Expat (aka libexpat) before 2.4.5 lacks certain validation of encoding, such as checks for whether a UTF-8 character is val40Plan
- CVE-2022-23852Expat (aka libexpat) before 2.4.4 has a signed integer overflow in XML_GetBuffer, for configurations with a nonzero XML_CONTEXT_BYTES.40Plan
- CVE-2022-22824defineAttribute in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.40Plan
- CVE-2022-22823build_model in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.40Plan
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 |
|---|---|---|
| github.com/libexpat/libexpat/ libexpat | 2.4.0 | Vendor (CNA) |
| debian:expat | 2.4.1-2 · Debian:12 | Package registry (OSV) |
| opensuse:expat | 2.4.1-1.2 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:python38 | 3.8.12-1.2 · openSUSE:Tumbleweed | Package registry (OSV) |
| red hat:expat | 0:2.4.9-1.el9_1 · Red Hat:enterprise_linux:9::baseos | Package registry (OSV) |
| red hat:expat-debuginfo | 0:2.4.9-1.el9_1 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:expat-debugsource | 0:2.4.9-1.el9_1 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:expat-devel | 0:2.4.9-1.el9_1 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| suse:expat | 2.7.1-1.1 · SUSE:Linux Micro 6.0 | 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
If successful
- Confidentiality
- P · data can be read
- Integrity
- P · data or configuration can be modified
- Availability
- P · the service can be disrupted
- Attack complexity
- M
- Confidentiality impact
- P
- Integrity impact
- P
- Availability impact
- P
Weakness class (CWE)
CWE-611 · Improper Restriction of XML External Entity ReferenceCVSS vector
AV:N/AC:M/Au:N/C:P/I:P/A:P
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)
ATT&CK techniques
—
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
- seclists.org/fulldisclosure/2021/Oct/61
- seclists.org/fulldisclosure/2021/Oct/62
- seclists.org/fulldisclosure/2021/Oct/63
- seclists.org/fulldisclosure/2021/Sep/33
- seclists.org/fulldisclosure/2021/Sep/34
- seclists.org/fulldisclosure/2021/Sep/35
- seclists.org/fulldisclosure/2021/Sep/38
- seclists.org/fulldisclosure/2021/Sep/39
- seclists.org/fulldisclosure/2021/Sep/40
- securitytracker.com/id?1028213
- www.openwall.com/lists/oss-security/2013/04/12/6
- www.openwall.com/lists/oss-security/2021/10/07/4
- www.osvdb.org/90634
- www.securityfocus.com/bid/58233
- github.com/libexpat/libexpat/blob/R_2_4_1/expat/Changes
- lists.apache.org/thread.html/r41eca5f4f09e74436cbb05dec450fc2bef37b5d3e966aa7cc5fada6d%40%3Cannounce.apache.org%3E
- lists.apache.org/thread.html/rfb2c193360436e230b85547e85a41bea0916916f96c501f5b6fc4702%40%3Cusers.openoffice.apache.org%3E
- security.gentoo.org/glsa/201701-21
- support.apple.com/kb/HT212804
- support.apple.com/kb/HT212805
Vendor advisories and official records. Exploit/PoC links are deliberately left out.