XML External Entity vulnerability in libexpat 2.2.0 and earlier (Expat XML Parser Library) allows attackers to put the parser in an infinite
XML External Entity vulnerability in libexpat 2.2.0 and earlier (Expat XML Parser Library) allows attackers to put the parser in an infinite loop using a malformed external entity definition from an external DTD.
Noroxi analysis
No Noroxi analysis for this record yet
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We use this product, ask for help- Published
- Jul 25, 2017
- Updated
- Jun 16, 2026
- EPSS
- 8.7% · 95th percentile
- CWE
- CWE-611
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Report tools
Action score
33
Monitor
Low priority for now.
- CVSS
- 30 / 40 · 7.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 3 / 30 · 8.7%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| libexpat project | libexpat | cpe:2.3:a:libexpat_project:libexpat |
| python | python | cpe:2.3:a:python:python |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- debian debian linux10.0
- debian debian linux8.0
- debian debian linux9.0
- libexpat project libexpatup to 2.2.0 inclusive
- python python3.5.0 and later · before 3.5.4
- python python3.6.0 and later · before 3.6.2
- python python3.4.0 and later · before 3.4.7
- python python3.3.0 and later · before 3.3.7
- python python2.7.0 and later · before 2.7.15
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Alpine:v3.10 | expat | before 2.2.0-r1 | 2.2.0-r1 |
| Debian:12 | expat | before 2.2.1-1 | 2.2.1-1 |
| Debian:12 | libxmltok | all versions | — |
| Debian:7 | expat | before 2.1.0-1+deb7u5 | 2.1.0-1+deb7u5 |
| Debian:8 | expat | before 2.1.0-6+deb8u4 | 2.1.0-6+deb8u4 |
| Debian:9 | expat | before 2.2.0-2+deb9u1 | 2.2.0-2+deb9u1 |
| openSUSE:Tumbleweed | expat | before 2.4.1-1.2 | 2.4.1-1.2 |
| SUSE:HPE Helion OpenStack 8 | python3 | before 3.4.10-25.39.3 | 3.4.10-25.39.3 |
| SUSE:HPE Helion OpenStack 8 | python3-base | before 3.4.10-25.39.2 | 3.4.10-25.39.2 |
| SUSE:Linux Enterprise Desktop 12 SP2 | expat | before 2.1.0-21.3.1 | 2.1.0-21.3.1 |
| SUSE:Linux Enterprise Software Development Kit 11 SP4 | expat | before 2.0.1-88.42.3.2 | 2.0.1-88.42.3.2 |
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 |
|---|---|---|
| alpine:expat | 2.2.0-r1 · Alpine:v3.10 | Package registry (OSV) |
| debian:expat | 2.2.1-1 · Debian:12 | Package registry (OSV) |
| opensuse:expat | 2.4.1-1.2 · openSUSE:Tumbleweed | Package registry (OSV) |
| suse:expat | 2.1.0-21.3.1 · SUSE:Linux Enterprise Desktop 12 SP2 | Package registry (OSV) |
| suse:python3 | 3.4.10-25.39.3 · SUSE:HPE Helion OpenStack 8 | Package registry (OSV) |
| suse:python3-base | 3.4.10-25.39.2 · SUSE:HPE Helion OpenStack 8 | 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
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-611 · Improper Restriction of XML External Entity ReferenceCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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)
ATT&CK techniques
—
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- support.apple.com/HT208113
- www.debian.org/security/2017/dsa-3898
- www.openwall.com/lists/oss-security/2017/06/17/7
- www.securityfocus.com/bid/99276
- www.securitytracker.com/id/1039427
- github.com/libexpat/libexpat/blob/master/expat/Changes
- lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E
- lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E
- support.apple.com/HT208112
- support.apple.com/HT208115
- support.apple.com/HT208144
- support.f5.com/csp/article/K03244804
Vendor advisories and official records. Exploit/PoC links are deliberately left out.