Quick answers
- Is CVE-2026-54998 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-54998 being exploited in the wild.
- How severe is CVE-2026-54998?
- High severity, with a CVSS score of 8.8, published 2 July 2026.
- Which products and versions are affected?
- Microsoft Exchange Online All versions.
- Is there a fix for CVE-2026-54998?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-54998 attacked?
- It is attacked over the network, in a hosted service.
- Am I affected by CVE-2026-54998?
- Check whether you run Microsoft Exchange Online at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
An incorrect authorization vulnerability (CWE-863) exists in Microsoft Exchange Online. The flaw allows a remote attacker with low-privileged credentials to bypass authorization checks and elevate their privileges within the environment. The attack vector is network-based and requires no user interaction, though it does require the attacker to be authenticated to the service. Successful exploitation could result in a total loss of confidentiality, integrity, and availability (CVSS 8.8). As this is a hosted service, Microsoft typically manages the deployment of fixes directly on the platform.
Affected products
- Microsoft Exchange Online All versions
Timeline
- 2026-07-02: advisory: Initial disclosure by Microsoft and NVD.