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CVE PROGRAM SOURCE RECORDUnscored

CVE-2026-23397

nfnetlink_osf: validate individual option lengths in fingerprints

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Status
Published
Published
Updated
Assigning organization
Linux

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 to < e9cf17b91e733fec725ebcc0b3098bc5ccd505e0affected
  • 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 to < 3c11b5c2436a3a5b450612ab160e3a525b28cfb5affected
  • 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 to < aa0574182c46963c3cdb8cde46ec93aca21100d8affected
  • 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 to < 224f4678812e1a7bc8341bcb666773a0aec5ea6faffected
  • 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 to < ec8bf0571b142f29dc0b68ae2ac3952f7a464b38affected
  • 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 to < 3932620c04c2938c93c0890c225960d3d34ba355affected
  • 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 to < 4c6aa008b913e808c4f4d3cde36cb1d9bb5967c6affected
  • 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 to < dbdfaae9609629a9569362e3b8f33d0a20fd783caffected

Linux Linux

Default version status: affected

  • 2.6.31affected
  • 0 to < 2.6.31unaffected
  • 5.10.253 to ≤ 5.10.*unaffected
  • 5.15.203 to ≤ 5.15.*unaffected
  • 6.1.167 to ≤ 6.1.*unaffected
  • 6.6.130 to ≤ 6.6.*unaffected
  • 6.12.78 to ≤ 6.12.*unaffected
  • 6.18.20 to ≤ 6.18.*unaffected
  • 6.19.10 to ≤ 6.19.*unaffected
  • 7.0 to ≤ *unaffected

References