Widely used Sentry platform; critical account takeover risk via SAML SSO forgery across many orgs.
CVE-2026-42354
Sentry SAML SSO flaw enables account takeover via malicious IdP.
Is CVE-2026-42354 being exploited?
Not confirmed. CVE-2026-42354 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.62% probability of exploitation in the next 30 days.
How severe is CVE-2026-42354?
CVE-2026-42354 is rated Critical with a CVSS score of 9.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-42354?
Yes. A fix has been recorded for CVE-2026-42354. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-42354 affect?
CVE-2026-42354 affects Sentry (SAML SSO), Versions 21.12.0 through 26.3.x. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-42354?
Patch to 26.4.1+, restart services, verify accounts.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Attacker can take over any user account on affected Sentry instances by forging a SAML assertion (needs victim email).
Immediate action required
- affected>= 21.12.0 and < 26.4.1
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.