CVE-2026-65801: Server-side request forgery (ssrf) in Microsoft Exchange Online allows an unauthorized attacker to elevate pri

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CRITICAL 10.0REMOTEWATCHLISTMITIGATE

CVE-2026-65801 is a critical-severity flaw (CVSS 10.0) affecting exchange online. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Server-side request forgery (ssrf) in Microsoft Exchange Online allows an unauthorized attacker to elevate privileges over a network.

Why this priority

Critical severity
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	10.0 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.9% (top 41%)
CISA exploited list	No
Weakness	CWE-918
Published	2026-08-20
Last modified	2026-10-18

Publisher (CNA): Microsoft Corporation · Vendor: microsoft

Last updated 2026-10-18 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-20 22:17 UTCPublished CVE record published
2026-10-18 20:10 UTCUpdated Record last modified

microsoft exchange online MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy exchange-online || rpm -q exchange-online || exchange-online --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora 46 · ruff · FIXED · 0.17.3-1.fc46 · FEDORA-2026-63898fdcbb · source

sudo dnf upgrade --advisory=FEDORA-2026-63898fdcbb

Fedora ELN · xorg-x11-server-Xwayland · FIXED · 26.0.99.903-2.eln159 · FEDORA-2026-4581dab0ed · source

sudo dnf upgrade --advisory=FEDORA-2026-4581dab0ed

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-65801?

exchange online: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-65801 being exploited?

CVE-2026-65801 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-65801 affect?

CVE-2026-65801 affects exchange online. Severity is critical (CVSS 10.0). Server-side request forgery (ssrf) in Microsoft Exchange Online allows an unauthorized attacker to elevate privileges over a network.

How urgent is CVE-2026-65801?

Priority 63/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Microsoft Exchange vulnerabilities

Related CVEs

CVE-2026-48582 CRITICAL 9.6 MITIGATE Missing authorization in Microsoft Exchange Online allows an authorized attacker to elevate privileges over a
CVE-2026-54998 HIGH 8.8 MITIGATE Incorrect authorization in Microsoft Exchange Online allows an authorized attacker to elevate privileges over
CVE-2026-56191 CRITICAL 10.0 MITIGATE Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over
CVE-2026-48579 CRITICAL 9.1 MITIGATE Improper authorization in Microsoft Exchange Online allows an unauthorized attacker to disclose information ov

References

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