VulnerabilityPublished 25 Sep 2026Updated 21 Oct 2026

CVE-2026-97566: Linux kernel · mptcp: pm: kernel: drop pending ADD_ADDR when removing ID0

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in d4a67a880654e1bfe318a31bea0bdbb026a09ade : update Linux kernel when convenient.

Data as of 26 Oct 2026, 14:18 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in d4a67a880654e1bfe318a31bea0bdbb026a09ade, bacf23e7c9876c9f4170166b3597cb22ea3ed39b, 545616b4e7325be3c61fc082538cb06d14f7b1db +2

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 740d798e8767d8a449902b1a1bbc70facfce19b5, < d4a67a880654e1bfe318a31bea0bdbb026a09ade	Fixed in d4a67a880654e1bfe318a31bea0bdbb026a09ade
LinuxLinux	Affected ≥ 740d798e8767d8a449902b1a1bbc70facfce19b5, < bacf23e7c9876c9f4170166b3597cb22ea3ed39b	Fixed in bacf23e7c9876c9f4170166b3597cb22ea3ed39b
LinuxLinux	Affected ≥ 740d798e8767d8a449902b1a1bbc70facfce19b5, < 545616b4e7325be3c61fc082538cb06d14f7b1db	Fixed in 545616b4e7325be3c61fc082538cb06d14f7b1db
LinuxLinux	Affected ≥ 740d798e8767d8a449902b1a1bbc70facfce19b5, < 189d60057e5f3d6a62e3d71a3cc428c9150bc14f	Fixed in 189d60057e5f3d6a62e3d71a3cc428c9150bc14f
LinuxLinux	Affected ≥ 740d798e8767d8a449902b1a1bbc70facfce19b5, < 2ac7d6e620764f1fc79eb4edd3610a7a661981ca	Fixed in 2ac7d6e620764f1fc79eb4edd3610a7a661981ca
LinuxLinux	Affected =5.13	Fixed in–

Description

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.

References

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