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MEDIUM severity

CVE-2026-37737 — sanic-cors

MEDIUM

CVE-2026-37737 is a medium-severity (CVSS 6.5) CWE-346 vulnerability in sanic-cors. No vendor fix is recorded yet; mitigation options are listed below.

sanic-cors contains an improper regular expression in the try_match() function

Also known asPYSEC-2026-3539
Published
Updated
Affected
1 pkg
Patched
None yet
Exploits
None indexed
Exploitation data as of Oct 17, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs14th percentile — riskier than 14% of all scored CVEsHighest risk
0.00%0.25%0.49%0.74%0.2%0.2%0.2%0.2%0.2%Jul 26Sep 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2026-37737 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 391,411 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🐍sanic-cors

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
🐍PyPIsanic-corsall versionsNo fix

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for sanic-cors, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Remediation status

    No patched version of sanic-cors has shipped for CVE-2026-37737 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

  3. Mitigate without a patch

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

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.
O3 Security · Impact-Aware SCA

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CVE-2026-37737: sanic-cors (Medium 6.5)