markdown2 is vulnerable to cross-site scripting
An issue was discovered in markdown2 (aka python-markdown2) through 2.3.5. The safe_mode feature, which is supposed to sanitize user input against XSS, is flawed and does not escape the input properly. With a crafted payload, XSS can be triggered, as demonstrated by omitting the final > character from an IMG tag.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | markdown2 | < 2.3.6 | 2.3.6 |
References
- https://github.com/trentm/python-markdown2/issues/285
- https://github.com/advisories/GHSA-p6h9-gw49-rqm4
- https://nvd.nist.gov/vuln/detail/CVE-2018-5773
- https://github.com/google/osv/issues/430
- https://github.com/trentm/python-markdown2/pull/303
- https://github.com/trentm/python-markdown2/commit/1b1dcdd727c0ef03453b9f5ef5ae3679f1d72323
- https://github.com/pypa/advisory-database/tree/main/vulns/markdown2/PYSEC-2018-13.yaml
- https://github.com/trentm/python-markdown2
- https://github.com/trentm/python-markdown2/blob/master/CHANGES.md#python-markdown2-236
- CVSS vector
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N- Weakness (CWE)
CWE-79- Platform
- Python (PyPI)
- Package
markdown2- Disclosed
- 18.01.2018
- Updated
- 11.10.2026 11:20
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2018-13 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-p6h9-gw49-rqm4 - CC BY 4.0
Vulnerability history: markdown2
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 4
- First → latest
- 01.2018 03.2021
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 1
- Medium 3
Disclosures per year
- 2018: 1
- 2019: 0
- 2020: 2
- 2021: 1
- 2022: 0
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 0
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markdown2 is vulnerable to cross-site scripting this entry
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