Affects Microsoft Exchange Server; widely used in enterprises; SSRF could leak internal data.
CVE-2026-45503
SSRF in Microsoft Exchange Server enables authenticated data disclosure.
Is CVE-2026-45503 being exploited?
Not confirmed. CVE-2026-45503 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 0.45% probability of exploitation in the next 30 days.
How severe is CVE-2026-45503?
CVE-2026-45503 is rated High with a CVSS score of 8.1. 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-2026-45503?
Yes. A fix has been recorded for CVE-2026-45503. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-45503 affect?
CVE-2026-45503 affects Microsoft Exchange Server. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-45503?
Patch ASAP when available; restrict access to Exchange; monitor for SSRF activity.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Authenticated SSRF allows disclosure of internal network data/resources via Exchange endpoints.
Patch when possible
- affected>= 15.01.0.0 and < 15.01.2507.071
- affected>= 15.02.0.0 and < 15.02.1544.043
- affected>= 15.02.0.0 and < 15.02.1748.048
- affected>= 15.02.0.0 and < 15.02.2562.045
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.