CVE-2026-44502 is a medium-severity (CVSS 4.3) Server-Side Request Forgery (SSRF) vulnerability in bugsink. A fix is available for bugsink — see the affected versions and patch details below.
Bugsink: SSRF bypass in `validate_webhook_url`
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-44502.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-44502 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
bugsinkReal-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
Summary
Bugsink’s webhook URL validation in versions 2.1.2 and earlier could be (partially) bypassed because of a mismatch in URL parsing.
In some malformed URLs, Python’s standard URL parser (urllib) and the HTTP client stack (requests / urllib3) do not agree on which host is actually being targeted. That could allow a webhook URL to pass Bugsink’s outbound-host checks while the actual HTTP request is sent somewhere else.
Impact
This issue affects Bugsink’s outbound webhook integrations.
An attacker who can supply or influence a webhook URL may be able to make Bugsink send an outbound HTTP POST request to a host that should have been blocked by the webhook validation logic, including loopback, private, or otherwise non-allowlisted destinations.
The practical impact is limited:
- this is an outbound webhook SSRF issue, not a general-purpose proxy
- Bugsink does not follow redirects for these webhook requests
- the request shape is constrained by how the malformed URL is normalized by the HTTP client
- this does not give arbitrary control over every possible request path
In other words, this is a real validation bypass, but it is narrower than a full arbitrary-request primitive.
Technical Details
The original validation logic parsed webhook URLs with Python’s urllib.parse.urlparse, then sent the request with requests.post.
For malformed inputs involving backslashes and @, those components can disagree about where the authority ends and which hostname is the real target. A URL may therefore appear to target an allowlisted public hostname during validation, while the HTTP client actually connects to a different host.
Fix
The fix has two parts:
- Bugsink now normalizes webhook URLs using the same HTTP client stack that will later send them, and applies validation to that normalized form.
- Bugsink now outright rejects raw webhook URLs containing characters outside the RFC URL character set, rather than relying on downstream normalization of malformed input.
Together, these changes remove the parser discrepancy and make webhook URL handling stricter and more predictable.
Workarounds
If users cannot upgrade immediately:
- restrict who can configure or modify webhook URLs
- review existing webhook configurations for malformed or unusual URLs
- prefer tightly controlled outbound network policy at the deployment level
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | bugsink | all versions | 2.1.3pip install --upgrade 'bugsink==2.1.3' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for bugsink, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update bugsink to 2.1.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-44502 is resolved across your whole dependency graph.
Workarounds
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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-44502 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-44502. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-44502 in your dependencies?
O3 Security finds CVE-2026-44502 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.