CVE-2026-55865 Python Liquid: Infinite loop when parsing malformed `{% case %}` tags
Malformed Liquid template tags cause an infinite loop during parsing, allowing attackers to trigger a denial of service in applications using the library.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-55865?
CVE-2026-55865 is a high-severity denial of service vulnerability in jg-rp liquid, published on 9 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Python Liquid is a Python engine for the Liquid template language. Prior to 2.2.1, given a malformed {% case %} tag without an associated {% when %} or {% else %} block and no terminating {% endcase %} tag, Python Liquid hangs in an infinite loop at parse time because liquid.TokenStream.eof did not give the EOF token matching kind and value fields, allowing malicious template authors to craft templates for a denial of service attack. This issue is fixed in version 2.2.1.
Weakness: CWE-835
Which versions are affected by CVE-2026-55865?
3 open source packages ship an affected version, including python-liquid.
| Package | Affected | Fixed in |
|---|---|---|
python-liquid PyPI | All versions | 2.2.1 |
python-liquid PyPI | All versions | 2.2.1 |
python-liquid PyPI | All versions | 2.2.1 |
How do I fix CVE-2026-55865?
Upgrade python-liquid to 2.2.1 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-55865 being exploited?
There is no known exploitation of CVE-2026-55865 in the wild and no public exploit code.
Sources
Also known as ECHO-3a95-2e3a-8c10, GHSA-vq2f-vcc9-j8mv, PYSEC-2026-3035.