High [CVE-2026-80586] reset DSS fields in case of unexpected size
This high-severity Red Hat Linux advisory covers CVE-2026-80586 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9.
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Summary
In the Linux kernel, the following vulnerability has been resolved: mptcp: options: reset DSS fields in case of unexpected size A remote peer could send a malformed DSS with a wrong size, followed by another DSS or MPC + Data.
In this case, the first suboption will be ignored, but leaving some fields written, which could lead to inconsistency or access uninitialized data. A flaw was found in the Linux kernel's Multipath TCP (mptcp) implementation.
This could lead to data inconsistency or the access of uninitialized data, potentially resulting in information disclosure or a denial of service. Red Hat severity: Important — CVSS 8.3 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H).
Weakness: CWE-824. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9.
Red Hat does not currently list a fixing RHSA for this CVE.
Affected products named by the advisory: Red Hat package: kernel-rt.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 11 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 11 days ago·verify at source
Mitigation checklist
- The vulnerability affects the Multipath TCP (MPTCP) feature in the Linux kernel. To mitigate this issue, MPTCP can be disabled by preventing the `mptcp` kernel module from loading. To disable the `mptcp` module: 1. Create a new file `/etc/modprobe.d/disable-mptcp.conf` with the following content: `install mptcp /bin/true blacklist mptcp` 2. Regenerate the initramfs to ensure the change takes effect on boot: `sudo dracut -f -v` 3. Reboot the system for the changes to take effect. Disabling MPTCP may impact network performance or functionality for applications that rely on Multipath TCP.
Official advisory · high-confidence parse· fetched 11 days ago·verify at source
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