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CVE-2026-23397

nfnetlink_osf: validate individual option lengths in fingerprints

HIGH 7.1

At a glance

Source
NVD
EPSS
EPSS 0.13 % · percentile 2 ()
State
PUBLISHED
Published
Updated
Assigner
Linux
NVD status
Modified

Description

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.

Weaknesses (CWE)

References

Scores

VersionScoreVectorScored by
CVSS 3.1HIGH 7.1CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:HNVD · nvd@nist.gov (Primary)

European references

CERT-FR advisories

Affected configurations (NVD CPE)

Affected products

ProductVersions
Linux · Linuxaffected 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 < e9cf17b91e733fec725ebcc0b3098bc5ccd505e0 ; affected 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 < 3c11b5c2436a3a5b450612ab160e3a525b28cfb5 ; affected 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 < aa0574182c46963c3cdb8cde46ec93aca21100d8 ; affected 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 < 224f4678812e1a7bc8341bcb666773a0aec5ea6f ; affected 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 < ec8bf0571b142f29dc0b68ae2ac3952f7a464b38 ; affected 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 < 3932620c04c2938c93c0890c225960d3d34ba355
Linux · Linuxaffected 2.6.31 ; unaffected 0 < 2.6.31 ; unaffected 5.10.253 ≤ 5.10.* ; unaffected 5.15.203 ≤ 5.15.* ; unaffected 6.1.167 ≤ 6.1.* ; unaffected 6.6.130 ≤ 6.6.*

Sources

SourceLicence
CVE List (CVEProject cvelistV5)CVE Program Terms of Use
EPSS (FIRST.org)FIRST — attribution requested
ENISA EUVDENISA — reproduction authorised, source acknowledged
CERT-FR (ANSSI)Licence Ouverte / Etalab 2.0
NVD (NIST) via fkie-cad/nvd-json-data-feedsPublic domain — this product uses data from the NVD API but is not endorsed or certified by the NVD