CVE-2026-7765: Incorrect authorization in the User Messages dashboard widget in Checkmk <2.5.0p5 causes the message-fetching

Q: How urgent is CVE-2026-7765?

Priority 29/100. Remotely exploitable, no login, no user action

Routine

MEDIUM 5.3REMOTEDOWNGRADE

CVE-2026-7765 is a medium-severity flaw (CVSS 5.3) affecting checkmk. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Incorrect authorization in the User Messages dashboard widget in Checkmk <2.5.0p5 causes the message-fetching endpoints to return the dashboard creator's messages rather than the viewer's, allowing an attacker who knows a valid public dashboard share token to read the issuer's personal messages by sending requests to the underlying endpoint, even without a User Messages widget present.

Why this priority

Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 77%)
CISA exploited list	No
Weakness	CWE-863
Published	2026-06-08
Last modified	2026-10-23

Publisher (CNA): Checkmk GmbH · Vendor: checkmk

Last updated 2026-10-23 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-08 13:16 UTCPublished CVE record published
2026-10-23 22:10 UTCUpdated Record last modified

checkmk checkmk DOWNGRADE

Affected: 2.5.0 · 2.5.0 b1 · 2.5.0 b2 · 2.5.0 b3 · 2.5.0 p1 · 2.5.0 p2 · 2.5.0 p3 · 2.5.0 p4

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.5.0

1. Check installed version

apt-cache policy checkmk || rpm -q checkmk || checkmk --version

2. No fixed release: DOWNGRADE to a release before 2.5.0 (Debian / Ubuntu)

apt-cache madison checkmk sudo apt install checkmk=<VERSION_BEFORE_2.5.0> sudo apt-mark hold checkmk

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

dnf --showduplicates list checkmk sudo dnf downgrade checkmk-<VERSION_BEFORE_2.5.0> sudo dnf versionlock add checkmk

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.

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-2026-7765?

checkmk: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-7765 being exploited?

CVE-2026-7765 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-2026-7765 affect?

CVE-2026-7765 affects checkmk. Severity is medium (CVSS 5.3). Incorrect authorization in the User Messages dashboard widget in Checkmk <2.5.0p5 causes the message-fetching endpoints to return the dashboard creator's messages rather than the viewer's, allowing an attacker who knows a valid public dashb

How urgent is CVE-2026-7765?

Priority 29/100. Remotely exploitable, no login, no user action

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References

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