Microsoft Teams is widely used; data disclosure via improper access control could affect many orgs and sensitive information.
CVE-2026-21535
Improper access control in Teams leaks information over network.
Is CVE-2026-21535 being exploited?
Not confirmed. CVE-2026-21535 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 0.59% probability of exploitation in the next 30 days.
How severe is CVE-2026-21535?
CVE-2026-21535 is rated High with a CVSS score of 8.2. 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-2026-21535?
Yes. A fix has been recorded for CVE-2026-21535. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-21535 affect?
CVE-2026-21535 affects Microsoft Teams. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-21535?
Monitor for data leakage; await patch; review access controls.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthorized disclosure of information via network by bypassing access controls in Teams.
Monitor only