CVE-2026-42354 is a critical-severity (CVSS 9.1) vulnerability in sentry. O3 Security confirms whether CVE-2026-42354 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Sentry: Improper authentication on SAML SSO process allows user identity linking
Real-World Exposure
sentryReal-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
Sentry is an error tracking and performance monitoring tool. From version 21.12.0 to before version 26.4.1, a critical vulnerability was discovered in the SAML SSO implementation of Sentry. The vulnerability allows an attacker to take over any user account by using a malicious SAML Identity Provider and another organization on the same Sentry instance. The victim email address must be known in order to exploit this vulnerability. This issue has been patched in version 26.4.1.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | sentry | ≥ 21.12.0&&< 26.4.1 | 26.4.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for sentry. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update sentry to 26.4.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-42354 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 pinpoints whether CVE-2026-42354 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-42354. 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-2026-42354 in your dependencies?
O3 detects CVE-2026-42354 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.