Is CVE-2026-55008 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-55008 being exploited in the wild.

How severe is CVE-2026-55008?

Critical severity, with a CVSS score of 9.6, published 14 July 2026.

Which products and versions are affected?

Microsoft Exchange Server 2016 < 15.01.2507.071; Microsoft Exchange Server 2019 < 15.02.1544.043; Microsoft Exchange Server Subscription Edition < 15.02.2562.045.

Is there a fix for CVE-2026-55008?

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-2026-55008 attacked?

It is attacked over the network, in a network appliance.

Am I affected by CVE-2026-55008?

Check whether you run Microsoft Exchange Server 2016, Microsoft Exchange Server 2019 or Microsoft Exchange Server Subscription Edition 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.

CVE-2026-55008: Microsoft Exchange Server cross-site scripting spoofing vulnerability

Q: Is there a fix for CVE-2026-55008?

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.

Q: How is CVE-2026-55008 attacked?

It is attacked over the network, in a network appliance.

Q: Am I affected by CVE-2026-55008?

Check whether you run Microsoft Exchange Server 2016, Microsoft Exchange Server 2019 or Microsoft Exchange Server Subscription Edition 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.

CVE-2026-55008 · Severity: critical · CVSS 9.6 · Published 2026-07-14

Microsoft Exchange Server, the widely used corporate email and calendaring platform, contains a critical security flaw that allows attackers to perform spoofing attacks. By tricking a user into interacting with a malicious link or page, an attacker can execute unauthorized actions in the context of that user's session. This could lead to the theft of sensitive communications, unauthorized access to mailboxes, or the compromise of user accounts.

Technologies: Microsoft Exchange Server 2016, Microsoft Exchange Server 2019, Microsoft Exchange Server Subscription Edition. Vendors: Microsoft.

Quick answers

Is CVE-2026-55008 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-55008 being exploited in the wild.
How severe is CVE-2026-55008?: Critical severity, with a CVSS score of 9.6, published 14 July 2026.
Which products and versions are affected?: Microsoft Exchange Server 2016 < 15.01.2507.071; Microsoft Exchange Server 2019 < 15.02.1544.043; Microsoft Exchange Server Subscription Edition < 15.02.2562.045.
Is there a fix for CVE-2026-55008?: 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-2026-55008 attacked?: It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-55008?: Check whether you run Microsoft Exchange Server 2016, Microsoft Exchange Server 2019 or Microsoft Exchange Server Subscription Edition 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

A critical cross-site scripting (XSS) vulnerability (CWE-79) exists in Microsoft Exchange Server due to improper neutralization of input during web page generation. The vulnerability is reachable over the network and requires minimal user interaction (typically clicking a link) to exploit. Because the vulnerability has a 'Changed' scope (S:C) and high impact on confidentiality, integrity, and availability, it allows an attacker to execute malicious scripts in the victim's browser session. This can lead to session token theft, unauthorized administrative actions, or full account takeover. Affected versions include Exchange Server 2016, 2019, and the Subscription Edition; users should apply the latest cumulative updates from Microsoft.

Affected products

Microsoft Exchange Server 2016 Cumulative Update 23 < 15.01.2507.071
Microsoft Exchange Server 2019 Cumulative Update 14 < 15.02.1544.043
Microsoft Exchange Server 2019 Cumulative Update 15 < 15.02.1748.048
Microsoft Exchange Server Subscription Edition RTM < 15.02.2562.045

Timeline

2026-07-14: disclosed
2026-07-14: advisory

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55008

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.