CVE-2026-89633: In the Linux kernel, the following vulnerability has been resolved: smb: client: fix OOB read/write from unva

This month

CRITICAL 9.8REMOTEWATCHLIST

CVE-2026-89633 is a critical-severity flaw (CVSS 9.8) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix OOB read/write from unvalidated DataOffset in coalesce_t2() coalesce_t2() computes data pointers directly from server-supplied DataOffset fields with no validation against buffer bounds: data_area_of_tgt = (char *)&pSMBt->hdr.Protocol + get_unaligned_le16(&pSMBt->t2_rsp.DataOffset); data_area_of_src = (char *)&pSMBs->hdr.Protocol +

Why this priority

Critical severity
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 58%)
CISA exploited list	No
Published	2026-09-11
Last modified	2026-10-21

Publisher (CNA): kernel.org

Last updated 2026-10-21 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Timeline

2026-09-11 20:19 UTCPublished CVE record published
2026-10-21 13:20 UTCUpdated Record last modified

Exact fixes by distribution

Fedora 46 · roundcubemail · FIXED · 1.7.5-1.fc46 · FEDORA-2026-669481bfa0 · source

sudo dnf upgrade --advisory=FEDORA-2026-669481bfa0

Fedora ELN · mozjs140 · FIXED · 140.13.0-5.eln159 · FEDORA-2026-f7ed0026e0 · source

sudo dnf upgrade --advisory=FEDORA-2026-f7ed0026e0

Debian 12 · linux · NO FIX YET

Debian 13 · linux · FIXED · 6.12.113-1

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.12.113-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 12 · linux-6.12 · FIXED · 6.12.113-1~deb12u1

sudo apt update && sudo apt install --only-upgrade linux-6.12 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux-6.12)" ge "6.12.113-1~deb12u1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 10 · kernel · FIXED · kernel-6.12.0-211.67.1.el10_2

sudo dnf upgrade --advisory=RHSA-2026:85321 rpm -q kernel

RHEL 9 · kernel · FIXED · kernel-5.14.0-687.59.1.el9_8

sudo dnf upgrade --advisory=RHSA-2026:86033 rpm -q kernel

RHEL 6 · kernel · NOT AFFECTED

RHEL 7 · kernel · NOT AFFECTED

RHEL 7 · kernel-rt · NOT AFFECTED

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-3187 · source

sudo dnf update --advisory=ALAS2023-2026-3187

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-89633?

No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.

Is CVE-2026-89633 being exploited?

CVE-2026-89633 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-89633 affect?

CVE-2026-89633 affects affected software. Severity is critical (CVSS 9.8). In the Linux kernel, the following vulnerability has been resolved: smb: client: fix OOB read/write from unvalidated DataOffset in coalesce_t2() coalesce_t2() computes data pointers directly from server-supplied DataOffset fields with no

How urgent is CVE-2026-89633?

Priority 55/100. Critical severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Linux kernel vulnerabilities

References

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