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CVE-2026-23397· NVD / CVE Program· CNA Linux

nfnetlink_osf: validate individual option lengths in fingerprints

Noroxi assessment

Priority: Monitor (action score 28/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.12% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 224f4678812e1a7bc8341bcb666773a0aec5ea6f, 3932620c04c2938c93c0890c225960d3d34ba355, 3c11b5c2436a3a5b450612ab160e3a525b28cfb5; azl3 kernel 6.6.126.1-1 on Azure Linux 3.0 6.6.130.1-1.

Low priority for now. Upgrade to Linux Linux 224f4678812e1a7bc8341bcb666773a0aec5ea6f, 3932620c04c2938c93c0890c225960d3d34ba355, 3c11b5c2436a3a5b450612ab160e3a525b28cfb5; azl3 kernel 6.6.126.1-1 on Azure Linux 3.0 6.6.130.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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: Oops: general protection fault KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: 0010:nf_osf_match_one (net/netfilter/nfnetlink_osf.c:98) Call Trace: nf_osf_match (net/netfilter/nfnetlink_osf.c:227) xt_osf_match_packet (net/netfilter/xt_osf.c:32) ipt_do_table (net/ipv4/netfilter/ip_tables.c:293) nf_hook_slow (net/netfilter/core.c:623) ip_local_deliver (net/ipv4/ip_input.c:262) ip_rcv (net/ipv4/ip_input.c:573) Additionally, an MSS option (kind=2) with length < 4 causes out-of-bounds reads when nf_osf_match_one() unconditionally accesses optp[2] and optp[3] for MSS value extraction. While RFC 9293 section 3.2 specifies that the MSS option is always exactly 4 bytes (Kind=2, Length=4), the check uses "< 4" rather than "!= 4" because lengths greater than 4 do not cause memory safety issues -- the buffer is guaranteed to be at least foptsize bytes by the ctx->optsize == foptsize check. Reject fingerprints where any option has zero length, or where an MSS option has length less than 4, at add time rather than trusting these values in the packet matching hot path.

HighCVSS 7.1 · v3.1—No exploit Fix available
Published
Mar 26, 2026
Updated
Oct 15, 2026
EPSS
0.1% · 1th percentile

Report tools

JSON

Action score

28

Monitor

Low priority for now.

CVSS
28 / 40 · 7.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel2.6.31.1 and later · before 5.10.253
  • linux linux kernel5.11 and later · before 5.15.203
  • linux linux kernel5.16 and later · before 6.1.167
  • linux linux kernel6.2 and later · before 6.6.130
  • linux linux kernel6.7 and later · before 6.12.78
  • linux linux kernel6.13 and later · before 6.18.20
  • linux linux kernel6.19 and later · before 6.19.10
  • linux linux kernel2.6.31
  • linux linux kernel7.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 2.6.31affected
    • 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 and later · before e9cf17b91e733fec725ebcc0b3098bc5ccd505e0affected · git
    • 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 and later · before 3c11b5c2436a3a5b450612ab160e3a525b28cfb5affected · git
    • 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 and later · before aa0574182c46963c3cdb8cde46ec93aca21100d8affected · git
    • 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 and later · before 224f4678812e1a7bc8341bcb666773a0aec5ea6faffected · git
    • 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 and later · before ec8bf0571b142f29dc0b68ae2ac3952f7a464b38affected · git
    • 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 and later · before 3932620c04c2938c93c0890c225960d3d34ba355affected · git
    • 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 and later · before 4c6aa008b913e808c4f4d3cde36cb1d9bb5967c6affected · git
    • 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 and later · before dbdfaae9609629a9569362e3b8f33d0a20fd783caffected · git
    • before 2.6.31not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.170-16.1.170-1
Debian:13linuxbefore 6.12.85-16.12.85-1
Debian:14linuxbefore 6.19.10-16.19.10-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now
  • CVE-2016-5195Race condition in mm/gup.c in the Linux kernel 2.x through 4.x before 4.8.3 allows local users to gain privileges by leveraging incorrect haKEV
    83Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-31788Mar 25, 2026 · xen/privcmd: restrict usage in unprivileged domU
    32Monitor
  • ← EarlierCVE-2026-23396Mar 26, 2026 · wifi: mac80211: fix NULL deref in mesh_matches_local()
    22Monitor
  • Later →CVE-2026-23398Mar 26, 2026 · icmp: fix NULL pointer dereference in icmp_tag_validation()
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux224f4678812e1a7bc8341bcb666773a0aec5ea6fVendor (CNA)
Linux Linux3932620c04c2938c93c0890c225960d3d34ba355Vendor (CNA)
Linux Linux3c11b5c2436a3a5b450612ab160e3a525b28cfb5Vendor (CNA)
Linux Linux4c6aa008b913e808c4f4d3cde36cb1d9bb5967c6Vendor (CNA)
Linux Linuxaa0574182c46963c3cdb8cde46ec93aca21100d8Vendor (CNA)
Linux Linuxdbdfaae9609629a9569362e3b8f33d0a20fd783cVendor (CNA)
Linux Linuxe9cf17b91e733fec725ebcc0b3098bc5ccd505e0Vendor (CNA)
Linux Linuxec8bf0571b142f29dc0b68ae2ac3952f7a464b38Vendor (CNA)
azl3 kernel 6.6.126.1-1 on Azure Linux 3.06.6.130.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.170-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (11 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records