CVSS 4.0
4.1 mediumCVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:NCVE-2026-128241 libexpat xmlwf through 2.10.0 Symlink Following via -d Output Directory
Medium (4.1) in libexpat project libexpat. EPSS 0.1% estimated probability of exploitation activity in the next 30 days.
On this page
The xmlwf tool in libexpat through 2.10.0 contains a symlink following vulnerability because -d output mode opens files with fopen("wb"), which follows symbolic links. Local attackers with write access to the output directory can plant a symlink at the expected output name to truncate or overwrite files writable by the xmlwf user.
Severity
CVSS 3.1
4.4 mediumCVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N- EPSS
- 0.1% estimated probability of exploitation activity in the next 30 days; 3rd percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
- CWE
- CWE-59 Improper Link Resolution Before File Access (Link Following)
- OWASP Top 10
- A01:2025 Broken Access Control
- Published
- Modified
- Assigned by
- VulnCheck (CNA)
- NVD analysis
- Awaiting analysis
- Record from
- the NVD, synced
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Affected
- libexpat project:libexpat
Versions
From the CNA's record in the CVE List.
| Product | Affected |
|---|---|
| libexpat project libexpat | through 2.10.0 |
Linux distributions
| Distribution | Release | Package | Fixed in | Advisory |
|---|---|---|---|---|
| Ubuntu | 16.04:LTS | gdcm, tdom, smart and 4 more | no fix listed | UBUNTU-CVE-2026-128241 |
| Ubuntu | 18.04:LTS | gdcm, tdom, vnc4 and 5 more | no fix listed | UBUNTU-CVE-2026-128241 |
| Ubuntu | 20.04:LTS | tdom, wbxml2, cadaver and 2 more | no fix listed | UBUNTU-CVE-2026-128241 |
| Ubuntu | 22.04:LTS | tdom, expat, wbxml2 and 3 more | no fix listed | UBUNTU-CVE-2026-128241 |
| Ubuntu | 24.04:LTS | tdom, expat, wbxml2 and 2 more | no fix listed | UBUNTU-CVE-2026-128241 |
| Ubuntu | 26.04:LTS | tdom, expat, wbxml2 and 3 more | no fix listed | UBUNTU-CVE-2026-128241 |
| Ubuntu | 26.10 | tdom, expat, wbxml2 and 4 more | no fix listed | UBUNTU-CVE-2026-128241 |
| Ubuntu | Pro:14.04:LTS | vtk, vnc4, coin3 and 2 more | no fix listed | UBUNTU-CVE-2026-128241 |
| Ubuntu | Pro:16.04:LTS | vtk, vnc4, ayttm and 6 more | no fix listed | UBUNTU-CVE-2026-128241 |
| Ubuntu | Pro:18.04:LTS | coin3, expat, swish-e and 2 more | no fix listed | UBUNTU-CVE-2026-128241 |
| Ubuntu | Pro:20.04:LTS | expat, swish-e, xmlrpc-c and 1 more | no fix listed | UBUNTU-CVE-2026-128241 |
| Ubuntu | Pro:22.04:LTS, Pro:24.04:LTS | swish-e, xmlrpc-c, libxmltok | no fix listed | UBUNTU-CVE-2026-128241 |
| 1 more for Ubuntu in the JSON and on Ubuntu's page. | ||||
From the distributions' data via OSV.dev: Ubuntu Security Notices © Canonical Ltd., CC BY-SA 4.0. Modified: reformatted and linked to CVE records. Credits. On the distributions' own pages: Ubuntu.
Attack patterns (CAPEC)
- CAPEC-17 Using Malicious Files Likelihood: High · Severity: Very High
- CAPEC-35 Leverage Executable Code in Non-Executable Files Likelihood: High · Severity: Very High
- CAPEC-76 Manipulating Web Input to File System Calls Likelihood: High · Severity: Very High
- CAPEC-132 Symlink Attack Likelihood: Low · Severity: High
The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.
References
- https://github.com/libexpat/libexpat
- https://github.com/libexpat/libexpat/blob/R_2_10_0/expat/xmlwf/xmlwf.c#L1272-L1275
- https://github.com/libexpat/libexpat/blob/R_2_10_0/expat/xmlwf/xmlwf.c#L1338-L1347
- https://github.com/libexpat/libexpat/pull/1502
- https://www.vulncheck.com/advisories/libexpat-xmlwf-through-2.10.0-symlink-following-via-d-output-directory