Linux Kernel up to 6.18.52/7.2.6/7.3-rc2 MPTCP Path Manager mptcp_pm_announced_alloc behavioral workflow

CVSS Meta Temp Score
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CTI Interest Score
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9.5$5k-$25k0.19

Summaryinfo

A vulnerability, which was classified as very critical, has been found in Linux Kernel up to 6.18.52/7.2.6/7.3-rc2. Affected by this vulnerability is the function mptcp_pm_announced_alloc of the component MPTCP Path Manager. This manipulation causes behavioral workflow. This vulnerability is tracked as CVE-2026-97566. The attack is possible to be carried out remotely. No exploit exists. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.18.52/7.2.6/7.3-rc2. It has been declared as very critical. Affected by this vulnerability is the function mptcp_pm_announced_alloc of the component MPTCP Path Manager. The manipulation with an unknown input leads to a behavioral workflow vulnerability. The CWE definition for the vulnerability is CWE-841. The product supports a session in which more than one behavior must be performed by an actor, but it does not properly ensure that the actor performs the behaviors in the required sequence. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: mptcp: pm: kernel: drop pending ADD_ADDR when removing ID0 The in-kernel MPTCP path manager can leave a stale ADD_ADDR announcement entry alive when removing the id 0 endpoint. This happens because the id 0 removal path does not tear down pending announcements, unlike the non-zero id path. When the PM later reselects id 0 after adding another signal endpoint, it finds the stale anno_list entry and hits WARN_ON_ONCE(mptcp_pm_is_kernel()) in mptcp_pm_announced_alloc(). Root cause: asymmetry between removal paths. - Non-zero id path: mptcp_nl_remove_subflow_and_signal_addr() calls mptcp_pm_remove_announced() to clean up. - Id 0 path: mptcp_nl_remove_id_zero_address() skips cleanup entirely. Fix by making the id 0 path symmetric: call mptcp_pm_announced_remove() and decrement add_addr_signaled before queuing the RM_ADDR. Subtle detail: signal endpoints are stored in anno_list with port 0, but msk_local carries the connection's local port. In other words, entries linked to ID0 paths should have port == 0. A follow-up patch will ensure that. mptcp_pm_announced_remove() uses use_port=true for comparison. So clear the port before the lookup.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2026-97566 since 09/24/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 09/25/2026).

Upgrading to version 6.18.53, 7.2.7 or 7.3-rc3 eliminates this vulnerability. Applying the patch d4a67a880654e1bfe318a31bea0bdbb026a09ade/545616b4e7325be3c61fc082538cb06d14f7b1db/2ac7d6e620764f1fc79eb4edd3610a7a661981ca is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

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Name

Version

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 10.0
VulDB Meta Temp Score: 9.5

VulDB Base Score: 10.0
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Behavioral workflow
CWE: CWE-841 / CWE-840
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.18.53/7.2.7/7.3-rc3
Patch: d4a67a880654e1bfe318a31bea0bdbb026a09ade/545616b4e7325be3c61fc082538cb06d14f7b1db/2ac7d6e620764f1fc79eb4edd3610a7a661981ca

Timelineinfo

09/24/2026 CVE reserved
09/25/2026 +1 days Advisory disclosed
09/25/2026 +0 days VulDB entry created
09/25/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-97566 (🔒)
GCVE (CVE): GCVE-0-2026-97566
GCVE (VulDB): GCVE-100-410047

Entryinfo

Created: 09/25/2026 14:08
Changes: 09/25/2026 14:08 (59)
Complete: 🔍
Cache ID: 216::103

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