# CVE-2026-37737: sanic-cors contains an improper regular expression in the try_match() function

> Attackers can bypass CORS origin allowlists via improper regex matching, gaining unauthorized access to authenticated cross-origin resources.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N`)
- **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:** No
- **Published:** 5 Jun 2026
- **Updated:** 5 Jun 2026
- **Also known as:** GHSA-94jw-hqvj-vw74, PYSEC-2026-3539

## What is CVE-2026-37737?

CVE-2026-37737 is a medium-severity vulnerability in n/a, published on 5 Jun 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

sanic-cors version 2.2.0 and prior contains an improper regular expression in the try_match() function in sanic_cors/core.py that uses re.match without end-anchoring. This allows an attacker to bypass CORS origin allowlists by registering a domain that begins with a trusted origin string, to gain unauthorized access to cross-origin requests for authenticated resources.

Weakness: CWE-625 (Permissive Regular Expression), CWE-346 (Origin Validation Error)

## Which versions are affected by CVE-2026-37737?

3 open source packages ship an affected version, including sanic-cors.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `sanic-cors` | PyPI | All versions to 2.2.0 | None |
| `sanic-cors` | PyPI | All versions to 2.2.0 | None |
| `sanic-cors` | PyPI | All versions to 2.2.0 | None |

## How do I fix CVE-2026-37737?

No fix has been published for CVE-2026-37737 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-37737 being exploited?

There is no known exploitation of CVE-2026-37737 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-37737 and fix it if it is affected.

What it is: CVE-2026-37737 is a medium-severity vulnerability in n/a, published on 5 Jun 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: There is no known exploitation of CVE-2026-37737 in the wild and no public exploit code.

Affected packages and fixed versions:
- sanic-cors (PyPI): affected all versions up to 2.2.0; no fix listed
- sanic-cors (PyPI): affected all versions up to 2.2.0; no fix listed
- sanic-cors (PyPI): affected all versions up to 2.2.0; no fix listed

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-2026-37737/ (Markdown: https://insights.sbomify.com/CVE-2026-37737/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-37737
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-37737
- OSV: https://osv.dev/vulnerability/CVE-2026-37737

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-37737/
Summaries are generated and may contain mistakes; the official description above is the record.