Checkmk up to 2.5.0p9 Agent Receiver improper authentication

Summaryinfo

A vulnerability classified as critical has been found in Checkmk. Affected is an unknown function of the component Agent Receiver. The manipulation leads to improper authentication. This vulnerability is referenced as CVE-2026-15576. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Checkmk. This issue affects some unknown processing of the component Agent Receiver. The manipulation with an unknown input leads to a improper authentication vulnerability. Using CWE to declare the problem leads to CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. Impacted is integrity, and availability. The summary by CVE is:

Improper authentication in the agent receiver of Checkmk <2.5.0p10 allows an unauthenticated remote attacker to bypass mutual TLS client certificate verification of relay endpoints by supplying a fixed placeholder identity in the request URL, resulting in limited impact on integrity and availability. Only the Cloud, Ultimate and Ultimate MT editions are affected, as other editions do not expose relay endpoints.

The advisory is shared at checkmk.com. The identification of this vulnerability is CVE-2026-15576 since 07/13/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Neither technical details nor an exploit are publicly available.

Upgrading to version 2.5.0p10 eliminates this vulnerability.

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Productinfo

Name

• Checkmk

Version

• 1.6.0p17
• 1.6.0p19
• 1.6.0p28
• 1.6.0p29
• 1.6.4
• 1.6.5
• 1.6.8
• 1.9.48
• 2.0.0p19
• 2.0.0p20
• 2.0.0p24
• 2.0.0p25
• 2.0.0p26
• 2.0.0p27
• 2.0.0p28
• 2.0.0p29
• 2.0.0p31
• 2.0.0p32
• 2.0.0p34
• 2.0.0p37
• 2.1.0b9
• 2.1.0b10
• 2.1.0p1
• 2.1.0p3
• 2.1.0p6
• 2.1.0p10
• 2.1.0p11
• 2.1.0p13
• 2.1.0p17
• 2.1.0p18
• 2.1.0p19
• 2.1.0p23
• 2.1.0p25
• 2.1.0p26
• 2.1.0p27
• 2.1.0p31
• 2.1.0p36
• 2.1.0p37
• 2.1.0p40
• 2.1.0p41
• 2.1.0p42
• 2.1.0p43
• 2.1.0p44
• 2.1.0p45
• 2.1.0p46
• 2.1.0p47
• 2.1.0p48
• 2.1.0p51
• 2.1.0p98
• 2.1.0p99
• 2.2.0
• 2.2.0b3
• 2.2.0b4
• 2.2.0b6
• 2.2.0b7
• 2.2.0i1
• 2.2.0p3
• 2.2.0p7
• 2.2.0p10
• 2.2.0p11
• 2.2.0p12
• 2.2.0p13
• 2.2.0p14
• 2.2.0p15
• 2.2.0p16
• 2.2.0p17
• 2.2.0p22
• 2.2.0p23
• 2.2.0p24
• 2.2.0p25
• 2.2.0p26
• 2.2.0p27
• 2.2.0p28
• 2.2.0p30
• 2.2.0p31
• 2.2.0p32
• 2.2.0p34
• 2.2.0p35
• 2.2.0p36
• 2.2.0p37
• 2.2.0p38
• 2.2.0p39
• 2.2.0p40
• 2.2.0p41
• 2.2.0p42
• 2.2.0p43
• 2.2.0p44
• 2.2.0p45
• 2.2.0p46
• 2.2.0p152.2.0p16
• 2.3.0
• 2.3.0b3
• 2.3.0b4
• 2.3.0b5
• 2.3.0p3
• 2.3.0p6
• 2.3.0p7
• 2.3.0p10
• 2.3.0p13
• 2.3.0p14
• 2.3.0p15
• 2.3.0p17
• 2.3.0p21
• 2.3.0p22
• 2.3.0p24
• 2.3.0p25
• 2.3.0p26
• 2.3.0p28
• 2.3.0p29
• 2.3.0p31
• 2.3.0p32
• 2.3.0p34
• 2.3.0p35
• 2.3.0p37
• 2.3.0p38
• 2.3.0p39
• 2.3.0p40
• 2.3.0p41
• 2.3.0p42
• 2.3.0p43
• 2.3.0p44
• 2.3.0p45
• 2.3.0p46
• 2.3.0p47
• 2.3.0p48
• 2.3.0p49
• 2.4.0
• 2.4.0b1
• 2.4.0b5
• 2.4.0b6
• 2.4.0b7
• 2.4.0p0
• 2.4.0p1
• 2.4.0p5
• 2.4.0p6
• 2.4.0p12
• 2.4.0p13
• 2.4.0p14
• 2.4.0p15
• 2.4.0p16
• 2.4.0p17
• 2.4.0p18
• 2.4.0p20
• 2.4.0p21
• 2.4.0p22
• 2.4.0p23
• 2.4.0p24
• 2.4.0p25
• 2.4.0p26
• 2.4.0p28
• 2.4.0p29
• 2.4.0p30
• 2.4.0p31
• 2.4.0p33
• 2.4.0p34
• 2.4.0p35
• 2.5.0b1
• 2.5.0b2
• 2.5.0b3
• 2.5.0b4
• 2.5.0p1
• 2.5.0p2
• 2.5.0p4
• 2.5.0p5
• 2.5.0p8
• 2.5.0p9

CPE 2.3info

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CPE 2.2info

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Entryinfo

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