Linux Kernel up to 7.0-rc4 nfnetlink_osf nfnetlink_osf.c nfnl_osf_add_callback out-of-bounds

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4.8$0-$5k0.00

Summaryinfo

A vulnerability categorized as critical has been discovered in Linux Kernel up to 7.0-rc4. Impacted is the function nfnl_osf_add_callback of the file net/netfilter/nfnetlink_osf.c of the component nfnetlink_osf. Executing a manipulation can lead to out-of-bounds. This vulnerability appears as CVE-2026-23397. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 7.0-rc4 and classified as problematic. This vulnerability affects the function nfnl_osf_add_callback of the file net/netfilter/nfnetlink_osf.c of the component nfnetlink_osf. The manipulation with an unknown input leads to a out-of-bounds vulnerability. The CWE definition for the vulnerability is CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. As an impact it is known to affect confidentiality. CVE summarizes:

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.

The advisory is available at git.kernel.org. This vulnerability was named CVE-2026-23397 since 01/13/2026. The exploitation appears to be difficult. Technical details are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 311783 (Debian dla-4561 : linux-config-6.1 - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10 or 7.0-rc5 eliminates this vulnerability. Applying the patch aa0574182c46963c3cdb8cde46ec93aca21100d8/224f4678812e1a7bc8341bcb666773a0aec5ea6f/ec8bf0571b142f29dc0b68ae2ac3952f7a464b38/3932620c04c2938c93c0890c225960d3d34ba355/4c6aa008b913e808c4f4d3cde36cb1d9bb5967c6/dbdfaae9609629a9569362e3b8f33d0a20fd783c is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (311783), EUVD (EUVD-2026-16157) and CERT Bund (WID-SEC-2026-0879). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

  • Open Source Linux Kernel

Productinfo

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Version

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.8
VulDB Meta Temp Score: 4.8

VulDB Base Score: 2.6
VulDB Temp Score: 2.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 7.1
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Out-of-bounds
CWE: CWE-125 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 311783
Nessus Name: Debian dla-4561 : linux-config-6.1 - security update

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.1.167/6.6.130/6.12.78/6.18.20/6.19.10/7.0-rc5
Patch: aa0574182c46963c3cdb8cde46ec93aca21100d8/224f4678812e1a7bc8341bcb666773a0aec5ea6f/ec8bf0571b142f29dc0b68ae2ac3952f7a464b38/3932620c04c2938c93c0890c225960d3d34ba355/4c6aa008b913e808c4f4d3cde36cb1d9bb5967c6/dbdfaae9609629a9569362e3b8f33d0a20fd783c

Timelineinfo

01/13/2026 CVE reserved
03/26/2026 +72 days Advisory disclosed
03/26/2026 +0 days VulDB entry created
07/16/2026 +112 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-23397 (🔒)
GCVE (CVE): GCVE-0-2026-23397
GCVE (VulDB): GCVE-100-353578
EUVD: 🔒
CERT Bund: WID-SEC-2026-0879 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 03/26/2026 13:21
Updated: 07/16/2026 22:18
Changes: 03/26/2026 13:21 (60), 04/09/2026 08:56 (7), 04/20/2026 00:14 (1), 05/04/2026 06:12 (2), 07/16/2026 22:18 (12)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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