Linux kernel SMB/CIFS client flaw affects widely deployed kernels, can cause remote memory corruption; widespread impact and high CVSS.
CVE-2026-89630
Linux kernel SMB client memory-corruption via oplock break check
Is CVE-2026-89630 being exploited?
Not confirmed. CVE-2026-89630 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.40% probability of exploitation in the next 30 days.
How severe is CVE-2026-89630?
CVE-2026-89630 is rated Critical with a CVSS score of 9.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-89630?
Yes. A fix has been recorded for CVE-2026-89630. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-89630 affect?
CVE-2026-89630 affects Linux kernel (CIFS/SMB client), Systems mounting SMB shares, Embedded Linux devices using SMB client. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-89630?
Apply vendor kernel updates or backported CIFS patches immediately
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote SMB server can trigger an out-of-bounds read/overflow in the SMB client, causing crashes, memory corruption and potential RCE.
Immediate action required
- affected>= 83bfbd0bb9025f98fa62b44f93bd67466773d1db and < 5b16a1967a01ad4496a7206a87c3eb16f1df2b05
- affected>= 83bfbd0bb9025f98fa62b44f93bd67466773d1db and < ba22f575de9deeae4ae0859ca4315a7698226237
- affected6.19
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.