VulnerabilityPublished 25 Sep 2026Updated 19 Oct 2026

CVE-2026-97568: Linux kernel · mptcp: syncookies: remember the request backup flag

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in c97fa2c7ada82d4cac1c6c00643238dc4c462f15 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 12:55 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in c97fa2c7ada82d4cac1c6c00643238dc4c462f15, b138e7dc719f0a3949de8bb6500b8cf1604eea06, b76c0e28b392620dfbaf92cdeedbf115820b44cb +10

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 >=5.10.224 <5.10.271 >=5.15.165 <5.15.222 >=6.1.104 <6.1.189 >=6.6.45 <6.6.158 >=6.10.4 <6.11	Fixed in c97fa2c7ada82d4cac1c6c00643238dc4c462f15 b138e7dc719f0a3949de8bb6500b8cf1604eea06 b76c0e28b392620dfbaf92cdeedbf115820b44cb 61178d0b85b4b1b53e78b06e89d018d22d102f88 1668b34452009d27be3262646de748a3e48ffd51 360d99258a6402cb8e49771460944f19f04d25b7 06d649f9cd03a9f8e768a658b20acf8d2c8022e0 6.11 6.6.158 6.1.189 5.15.222 5.10.271 00b2bd518911e0daab00f4749cce68c191ccebb4
LinuxLinux	Affected =6.11	Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: mptcp: syncookies: remember the request backup flag Instead of using an uninitialised bit when copying the info in subflow_ulp_clone(). To fix this, no need to extend the join_entry structure: backup is coming from struct mptcp_subflow_request_sock, only one bit. Do the same here by using one bit for both.

References

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