PT-2026-27686 · Linux · Linux Kernel

Published 2026-01-01 · Updated 2026-04-20 · CVE-2026-23321

Positive Technologies (AI Summary)

CVSS v3.1

5.5

Medium

Base vector

AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Name of the Vulnerable Software and Affected Versions Linux kernel versions prior to 6.19.0-08368-gfafda3b4b06b #22

Description The Linux kernel contains a flaw related to MPTCP (Multipath TCP) path management. A specific sequence of actions, involving setting the MPTCP subflows limit to zero, creating an MPTCP endpoint with both 'signal' and 'subflow' flags, creating a new MPTCP connection with an address addition linked to the endpoint (using the 'signal' flag but not initiating subflows with the 'subflow' flag), and then removing the endpoint, can trigger a warning indicating an issue with marking the endpoint as used. This can lead to unexpected behavior within the MPTCP subsystem.

Recommendations Update to Linux kernel version 6.19.0-08368-gfafda3b4b06b #22 or a later version to address this issue.

Exploit

Fix

Related Identifiers

CVE-2026-23321

ECHO-93A1-09CC-3063

OESA-2026-1862

OESA-2026-1863

OESA-2026-1864

OPENSUSE-SU-2026:20826-1

SUSE-SU-2026:21841-1

Affected Products

Linux Kernel

References · 73

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23321.json · Exploit
• https://git.kernel.org/stable/c/c5c877e140e5f46023a74a51e577ce5edd0a4be7 · Patch
• https://nvd.nist.gov/vuln/detail/CVE-2026-23240 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-23321 · Security Note
• https://git.kernel.org/stable/c/05799c2f1ca5eb13d65764dda688d02021b65e06 · Patch
• https://osv.dev/vulnerability/UBUNTU-CVE-2026-23321 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-23413 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-31788 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-23293 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-23278 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-23392 · Security Note
• https://cve.org/CVERecord?id=CVE-2026-23321 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-23277 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-23300 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-23255 · Security Note