CVE-2026-31709: In the Linux kernel, the following vulnerability has been resolved: smb: client: validate the whole DACL befo

Q: How do I fix CVE-2026-31709?

linux kernel: upgrade to 7.0.2. Exact commands for each OS are on this page.

Q: Is CVE-2026-31709 being exploited?

CVE-2026-31709 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-31709 affect?

CVE-2026-31709 affects linux kernel. Severity is high (CVSS 8.8). In the Linux kernel, the following vulnerability has been resolved: smb: client: validate the whole DACL before rewriting it in cifsacl build_sec_desc() and id_mode_to_cifs_acl() derive a DACL pointer from a server-supplied dacloffset and

Q: How urgent is CVE-2026-31709?

Priority 43/100. High severity; On your watchlist

This month

HIGH 8.8WATCHLISTUPGRADE

CVE-2026-31709 is a high-severity flaw (CVSS 8.8) affecting linux kernel. 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: validate the whole DACL before rewriting it in cifsacl build_sec_desc() and id_mode_to_cifs_acl() derive a DACL pointer from a server-supplied dacloffset and then use the incoming ACL to rebuild the chmod/chown security descriptor. The original fix only checked that the struct smb_acl header fits before reading dacl_ptr->size or dacl_ptr->num_aces. That avoids th

Why this priority

High severity
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.3% (top 72%)
CISA exploited list	No
Weakness	CWE-125, CWE-1288
Published	2026-05-01
Last modified	2026-10-19

Publisher (CNA): kernel.org · Vendor: linux

Last updated 2026-10-19 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-01 14:16 UTCPublished CVE record published
2026-10-19 20:17 UTCUpdated Record last modified

linux linux kernel UPGRADE

Affected: >= 5.12 and < 7.0.2

Fixed in: 7.0.2

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2026-31709?

linux kernel: upgrade to 7.0.2. Exact commands for each OS are on this page.

Is CVE-2026-31709 being exploited?

CVE-2026-31709 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-2026-31709 affect?

CVE-2026-31709 affects linux kernel. Severity is high (CVSS 8.8). In the Linux kernel, the following vulnerability has been resolved: smb: client: validate the whole DACL before rewriting it in cifsacl build_sec_desc() and id_mode_to_cifs_acl() derive a DACL pointer from a server-supplied dacloffset and

How urgent is CVE-2026-31709?

Priority 43/100. High severity; On your watchlist

Software pages

Linux kernel vulnerabilities

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References

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