# CVE-2026-126193: Denial of service in soupsieve

> Deeply nested CSS selectors can exhaust the Python stack in apps using Soup Sieve, crashing the request.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Harmful if only installed:** No
- **Needs a specific call:** Yes
- **Fix available:** No
- **Published:** 12 Nov 2026
- **Updated:** 12 Nov 2026
- **Also known as:** GHSA-7g44-g9rc-x53w

## What is CVE-2026-126193?

CVE-2026-126193 is a medium-severity denial of service vulnerability in facelessuser soupsieve, published on 12 Nov 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Soup Sieve is a CSS selector library for Beautiful Soup. From 0.4 until 3.0, deeply nested CSS pseudo-class selectors can cause recursive parsing to exceed Python’s recursion limit and raise  RecursionError . Applications accepting untrusted selectors may experience failure of the affected request or task if the exception is not handled. The demonstrated behavior is recoverable and does not establish an interpreter crash or persistent service-wide denial of service. This vulnerability is fixed in version 3.0.

Weakness: CWE-674 (Uncontrolled Recursion)

## Which versions are affected by CVE-2026-126193?

An affected version is only exploitable if your software uses the vulnerable function or option. Many projects that include it are not exposed.


## How do I fix CVE-2026-126193?

No fix has been published for CVE-2026-126193 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-126193 being exploited?

There is no known exploitation of CVE-2026-126193 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-126193 and fix it if it is affected.

What it is: CVE-2026-126193 is a medium-severity denial of service vulnerability in facelessuser soupsieve, published on 12 Nov 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-126193 in the wild and no public exploit code.
Exposure: An affected version is only exploitable if your software uses the vulnerable function or option. Many projects that include it are not exposed.

Affected product: facelessuser soupsieve. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-126193/ (Markdown: https://insights.sbomify.com/CVE-2026-126193/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-126193
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-126193
- OSV: https://osv.dev/vulnerability/CVE-2026-126193

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-126193/
Summaries are generated and may contain mistakes; the official description above is the record.