CVE-2026-49825 lxml: javascript: URL bypass in Cleaner via xlink:href
High 8.2
Published
Updated
Check this codebase for CVE-2026-49825 and fix it if it is affected.
What it is: CVE-2026-49825 is a high-severity cross-site scripting vulnerability in fedora-python lxml, published on 20 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49825 exists.
Affected packages and fixed versions:
- lxml-html-clean (PyPI): affected all versions; fixed in 0.4.5
- lxml-html-clean (PyPI): affected all versions; fixed in 0.4.5
- lxml_html_clean (PyPI): affected all versions; fixed in 0.4.5
Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.
Reference: https://insights.sbomify.com/CVE-2026-49825/ (Markdown: https://insights.sbomify.com/CVE-2026-49825/index.md)
Attackers can bypass HTML cleaner protections using xlink:href attributes in SVG content to inject malicious JavaScript, leading to XSS.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-49825?
CVE-2026-49825 is a high-severity cross-site scripting vulnerability in fedora-python lxml, published on 20 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
lxml is a library for processing XML and HTML in the Python language. Prior to 6.1.1, link attributes in ``lxml.html.defs.link_attrs`` were missing ``xlink:href``, which can be used for URL bypass attacks in embedded SVG/MathML/etc. content. This vulnerability was fixed in lxml 6.1.1 and lxml_html_clean 0.4.5.
Which versions are affected by CVE-2026-49825?
3 open source packages ship an affected version, including lxml-html-clean and lxml_html_clean.
| Package | Affected | Fixed in |
|---|---|---|
lxml-html-clean PyPI | All versions | 0.4.5 |
lxml-html-clean PyPI | All versions | 0.4.5 |
lxml_html_clean PyPI | All versions | 0.4.5 |
Linux distribution packages (37)
python3-lxml AlmaLinux:8 | All versions | 4.2.3-5.el8_10 |
python3-lxml AlmaLinux:9 | All versions | 4.6.5-3.el9_8.1 |
python3.12-lxml AlmaLinux:9 | All versions | 4.9.3-2.el9_8.1 |
python-lxml Red Hat:enterprise_linux:8::appstream | All versions | 0:4.2.3-5.el8_10 |
python-lxml-debugsource Red Hat:enterprise_linux:8::appstream | All versions | 0:4.2.3-5.el8_10 |
python3-lxml Red Hat:enterprise_linux:8::appstream | All versions | 0:4.2.3-5.el8_10 |
python3-lxml-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:4.2.3-5.el8_10 |
python-lxml Red Hat:enterprise_linux:9::appstream | All versions | 0:4.6.5-3.el9_8.1 |
python-lxml-debugsource Red Hat:enterprise_linux:9::appstream | All versions | 0:4.6.5-3.el9_8.1 |
python3-lxml Red Hat:enterprise_linux:9::appstream | All versions | 0:4.6.5-3.el9_8.1 |
python3-lxml-debuginfo Red Hat:enterprise_linux:9::appstream | All versions | 0:4.6.5-3.el9_8.1 |
python3.12-lxml Red Hat:enterprise_linux:9::appstream | All versions | 0:4.9.3-2.el9_8.1 |
python3.12-lxml-debuginfo Red Hat:enterprise_linux:9::appstream | All versions | 0:4.9.3-2.el9_8.1 |
python3.12-lxml-debugsource Red Hat:enterprise_linux:9::appstream | All versions | 0:4.9.3-2.el9_8.1 |
python-lxml Red Hat:rhel_aus:8.6::appstream | All versions | 0:4.2.3-4.el8_6.1 |
python-lxml-debugsource Red Hat:rhel_aus:8.6::appstream | All versions | 0:4.2.3-4.el8_6.1 |
python3-lxml Red Hat:rhel_aus:8.6::appstream | All versions | 0:4.2.3-4.el8_6.1 |
python3-lxml-debuginfo Red Hat:rhel_aus:8.6::appstream | All versions | 0:4.2.3-4.el8_6.1 |
python-lxml Red Hat:rhel_e4s:8.8::appstream | All versions | 0:4.2.3-4.el8_8.1 |
python-lxml-debugsource Red Hat:rhel_e4s:8.8::appstream | All versions | 0:4.2.3-4.el8_8.1 |
python3-lxml Red Hat:rhel_e4s:8.8::appstream | All versions | 0:4.2.3-4.el8_8.1 |
python3-lxml-debuginfo Red Hat:rhel_e4s:8.8::appstream | All versions | 0:4.2.3-4.el8_8.1 |
python-lxml Red Hat:rhel_e4s:9.2::appstream | All versions | 0:4.6.5-3.el9_2.1 |
python-lxml-debugsource Red Hat:rhel_e4s:9.2::appstream | All versions | 0:4.6.5-3.el9_2.1 |
python3-lxml Red Hat:rhel_e4s:9.2::appstream | All versions | 0:4.6.5-3.el9_2.1 |
python3-lxml-debuginfo Red Hat:rhel_e4s:9.2::appstream | All versions | 0:4.6.5-3.el9_2.1 |
python-lxml Red Hat:rhel_e4s:9.4::appstream | All versions | 0:4.6.5-3.el9_4.1 |
python-lxml-debugsource Red Hat:rhel_e4s:9.4::appstream | All versions | 0:4.6.5-3.el9_4.1 |
python3-lxml Red Hat:rhel_e4s:9.4::appstream | All versions | 0:4.6.5-3.el9_4.1 |
python3-lxml-debuginfo Red Hat:rhel_e4s:9.4::appstream | All versions | 0:4.6.5-3.el9_4.1 |
python3.12-lxml Red Hat:rhel_e4s:9.4::appstream | All versions | 0:4.9.3-2.el9_4.1 |
python3.12-lxml-debuginfo Red Hat:rhel_e4s:9.4::appstream | All versions | 0:4.9.3-2.el9_4.1 |
python3.12-lxml-debugsource Red Hat:rhel_e4s:9.4::appstream | All versions | 0:4.9.3-2.el9_4.1 |
python-lxml Red Hat:rhel_eus:9.6::appstream | All versions | 0:4.6.5-3.el9_6.1 |
python-lxml-debugsource Red Hat:rhel_eus:9.6::appstream | All versions | 0:4.6.5-3.el9_6.1 |
python3-lxml Red Hat:rhel_eus:9.6::appstream | All versions | 0:4.6.5-3.el9_6.1 |
python3-lxml-debuginfo Red Hat:rhel_eus:9.6::appstream | All versions | 0:4.6.5-3.el9_6.1 |
How do I fix CVE-2026-49825?
Upgrade lxml-html-clean to 0.4.5 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-49825 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49825 exists.
Sources
Also known as ALSA-2026:66203, ALSA-2026:66204, ALSA-2026:67943, AZL-96857, BELL-CVE-2026-49825, CLSA-2026-1792809744 and 23 more.