CVE-2026-23397: In the Linux kernel, the following vulnerability has been resolved: nfnetlink_osf: validate individual option

Q: How do I fix CVE-2026-23397?

linux kernel: upgrade to 5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10. Exact commands for each OS are on this page.

Q: Is CVE-2026-23397 being exploited?

CVE-2026-23397 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-2026-23397 affect?

CVE-2026-23397 affects linux kernel. Severity is high (CVSS 7.1). In the Linux kernel, the following vulnerability has been resolved: nfnetlink_osf: validate individual option lengths in fingerprints nfnl_osf_add_callback() validates opt_num bounds and string NUL-termination but does not check individua

Q: How urgent is CVE-2026-23397?

Priority 30/100. High severity; On your watchlist

Routine

HIGH 7.1WATCHLISTUPGRADE

CVE-2026-23397 is a high-severity flaw (CVSS 7.1) 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: nfnetlink_osf: validate individual option lengths in fingerprints nfnl_osf_add_callback() validates opt_num bounds and string NUL-termination but does not check individual option length fields. A zero-length option causes nf_osf_match_one() to enter the option matching loop even when foptsize sums to zero, which matches packets with no TCP options where ctx->optp is NULL: Oop

Why this priority

High severity
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.1 (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-125
Published	2026-03-26
Last modified	2026-10-15

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

Last updated 2026-10-15 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-26 11:16 UTCPublished CVE record published
2026-10-15 02:18 UTCUpdated Record last modified

linux linux kernel UPGRADE

Affected: >= 2.6.31.1 and < 5.10.253 · >= 5.11 and < 5.15.203 · >= 5.16 and < 6.1.167 · >= 6.2 and < 6.6.130 · >= 6.7 and < 6.12.78 · >= 6.13 and < 6.18.20 · >= 6.19 and < 6.19.10 · 2.6.31

Fixed in: 5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10

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-2026-23397?

linux kernel: upgrade to 5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10. Exact commands for each OS are on this page.

Is CVE-2026-23397 being exploited?

CVE-2026-23397 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-2026-23397 affect?

CVE-2026-23397 affects linux kernel. Severity is high (CVSS 7.1). In the Linux kernel, the following vulnerability has been resolved: nfnetlink_osf: validate individual option lengths in fingerprints nfnl_osf_add_callback() validates opt_num bounds and string NUL-termination but does not check individua

How urgent is CVE-2026-23397?

Priority 30/100. High severity; On your watchlist

Software pages

Linux kernel vulnerabilities

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References

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