CVE-2026-69356: Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Ser

Q: How do I fix CVE-2026-69356?

exchange server: downgrade or apply the listed mitigation; exchange server subscription edition: upgrade to 15.02.2562.049. Exact commands for each OS are on this page.

Q: Is CVE-2026-69356 being exploited?

CVE-2026-69356 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-69356 affect?

CVE-2026-69356 affects exchange server, exchange server subscription edition. Severity is critical (CVSS 9.3). Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.

Q: How urgent is CVE-2026-69356?

Priority 51/100. Critical severity; On your watchlist

This month

CRITICAL 9.3WATCHLISTDOWNGRADEUPGRADE

CVE-2026-69356 is a critical-severity flaw (CVSS 9.3) affecting exchange server, exchange server subscription edition. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.

Why this priority

Critical severity
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.3 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.8% (top 45%)
CISA exploited list	No
Weakness	CWE-79
Published	2026-09-08
Last modified	2026-09-30

Publisher (CNA): Microsoft Corporation · Vendor: microsoft

Last updated 2026-09-30 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-08 18:18 UTCPublished CVE record published
2026-09-30 12:29 UTCUpdated Record last modified

microsoft exchange server DOWNGRADE

Affected: 2016 cumulative_update_23 · 2019 cumulative_update_14 · 2019 cumulative_update_15

Fixed in: no fixed release known

Safe to downgrade to: a release before 2016

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2016 (Debian / Ubuntu)

apt-cache madison exchange-server sudo apt install exchange-server=<VERSION_BEFORE_2016> sudo apt-mark hold exchange-server

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list exchange-server sudo dnf downgrade exchange-server-<VERSION_BEFORE_2016> sudo dnf versionlock add exchange-server

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

microsoft exchange server subscription edition UPGRADE

Affected: < 15.02.2562.049

Fixed in: 15.02.2562.049

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy exchange-server-subscription-edition || rpm -q exchange-server-subscription-edition || exchange-server-subscription-edition --version

2. UPGRADE to 15.02.2562.049 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade exchange-server-subscription-edition

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade exchange-server-subscription-edition

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2026-69356?

exchange server: downgrade or apply the listed mitigation; exchange server subscription edition: upgrade to 15.02.2562.049. Exact commands for each OS are on this page.

Is CVE-2026-69356 being exploited?

CVE-2026-69356 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-2026-69356 affect?

CVE-2026-69356 affects exchange server, exchange server subscription edition. Severity is critical (CVSS 9.3). Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.

How urgent is CVE-2026-69356?

Priority 51/100. Critical severity; On your watchlist

Software pages

Microsoft Exchange vulnerabilities

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References

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