CVE-2026-97523
Description
A flaw was found in the Linux kernel's MultiPath TCP (MPTCP) subsystem. A race condition between the packet scheduler and socket state transitions can cause the maximum segment size to be reset to zero following a transmission failure. An attacker could exploit this flaw during connection handling to trigger a division-by-zero error during socket release, leading to a kernel crash and a Denial of Service (DoS).
Statement
A moderate-impact race condition flaw was found in the Linux kernel's MultiPath TCP (MPTCP) subsystem. If the MPTCP packet scheduler races with a subflow socket state change, data transmission on the selected subflow can fail and leave the maximum segment size (mss_now) reset to zero; a subsequent socket release can then perform a division by zero in tcp_push(), causing a kernel panic and a denial of service. An unprivileged local user who can create and transmit data on MPTCP sockets and win this timing-dependent race can crash the system; confidentiality and integrity are not affected. Red Hat Enterprise Linux 6 and 7 are not affected because the vulnerable code is not present. The kernel packages in Red Hat Enterprise Linux 8, 9, and 10, Red Hat In-Vehicle OS, and the RHEL CoreOS kernels used by OpenShift Container Platform are affected, with fixes currently deferred; no fixed packages are available at this time, and the residual risk is local denial of service on systems where untrusted local users can use MPTCP sockets. Red Hat rates this flaw moderate (CVSS 5.5, AV:L/AC:L/PR:L) rather than the upstream 7.5 network severity, because triggering the race requires local execution of MPTCP socket operations on the affected host.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | N/A | 7.5 |
| Attack Vector | Local | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
A Divide by Zero results in a crash.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
