Medium [CVE-2026-89630] Linux kernel: SMB client read overflow vulnerability in oplock break handling
This medium-severity Red Hat Linux advisory covers CVE-2026-89630 affecting Red Hat OpenShift Container Platform 4.
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Summary
A flaw was found in the Linux kernel's Server Message Block (SMB) client. An incorrect calculation of the `data_offset` bound in the `is_valid_oplock_break()` function can lead to a read overflow.
This vulnerability allows a malicious SMB server to potentially trigger an out-of-bounds read, which could result in information disclosure or a denial of service. Red Hat severity: Moderate — CVSS 6.3 (CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:H).
Weakness: CWE-125. Affected Red Hat products: Red Hat OpenShift Container Platform 4.
Red Hat does not currently list a fixing RHSA for this CVE.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 22 minutes 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 · medium-confidence parse· fetched 22 minutes ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 22 minutes ago·verify at source
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