CVE-2026-31666: In the Linux kernel, the following vulnerability has been resolved: btrfs: fix incorrect return value after c

Q: How do I fix CVE-2026-31666?

linux kernel: upgrade to 6.12.82, 6.18.23, 6.19.13. Exact commands for each OS are on this page.

Q: Is CVE-2026-31666 being exploited?

CVE-2026-31666 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-2026-31666 affect?

CVE-2026-31666 affects linux kernel. Severity is high (CVSS 7.8). In the Linux kernel, the following vulnerability has been resolved: btrfs: fix incorrect return value after changing leaf in lookup_extent_data_ref() After commit 1618aa3c2e01 ("btrfs: simplify return variables in lookup_extent_data_ref()

Q: How urgent is CVE-2026-31666?

Priority 33/100. High severity; On your watchlist

Routine

HIGH 7.8WATCHLISTUPGRADE

CVE-2026-31666 is a high-severity flaw (CVSS 7.8) 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: btrfs: fix incorrect return value after changing leaf in lookup_extent_data_ref() After commit 1618aa3c2e01 ("btrfs: simplify return variables in lookup_extent_data_ref()"), the err and ret variables were merged into a single ret variable. However, when btrfs_next_leaf() returns 0 (success), ret is overwritten from -ENOENT to 0. If the first key in the next leaf does not match

Why this priority

High severity
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.1% (top 98%)
CISA exploited list	No
Weakness	CWE-754
Published	2026-04-24
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

2026-04-24 15:16 UTCPublished CVE record published
2026-10-19 19:18 UTCUpdated Record last modified

linux linux kernel UPGRADE

Affected: >= 6.10.1 and < 6.12.82 · >= 6.13 and < 6.18.23 · >= 6.19 and < 6.19.13 · 6.10 · 7.0 rc1 · 7.0 rc2 · 7.0 rc3 · 7.0 rc4

Fixed in: 6.12.82, 6.18.23, 6.19.13

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-2026-31666?

linux kernel: upgrade to 6.12.82, 6.18.23, 6.19.13. Exact commands for each OS are on this page.

Is CVE-2026-31666 being exploited?

CVE-2026-31666 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-2026-31666 affect?

CVE-2026-31666 affects linux kernel. Severity is high (CVSS 7.8). In the Linux kernel, the following vulnerability has been resolved: btrfs: fix incorrect return value after changing leaf in lookup_extent_data_ref() After commit 1618aa3c2e01 ("btrfs: simplify return variables in lookup_extent_data_ref()

How urgent is CVE-2026-31666?

Priority 33/100. High severity; On your watchlist

Software pages

Linux kernel vulnerabilities

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References

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