nfnetlink_osf: validate individual option lengths in fingerprints

MITRE NVD CVE.ORG Print: PDF PDF

Summary

CVECVE-2026-23397
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-26 11:16:19 UTC
Updated2026-03-30 13:26:50 UTC
DescriptionIn 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.

Risk And Classification

EPSS: 0.000320000 probability, percentile 0.091740000 (date 2026-04-01)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 aa0574182c46963c3cdb8cde46ec93aca21100d8 git Not specified
CNA Linux Linux affected 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 224f4678812e1a7bc8341bcb666773a0aec5ea6f git Not specified
CNA Linux Linux affected 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 ec8bf0571b142f29dc0b68ae2ac3952f7a464b38 git Not specified
CNA Linux Linux affected 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 3932620c04c2938c93c0890c225960d3d34ba355 git Not specified
CNA Linux Linux affected 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 4c6aa008b913e808c4f4d3cde36cb1d9bb5967c6 git Not specified
CNA Linux Linux affected 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 dbdfaae9609629a9569362e3b8f33d0a20fd783c git Not specified
CNA Linux Linux affected 2.6.31 Not specified
CNA Linux Linux unaffected 2.6.31 semver Not specified
CNA Linux Linux unaffected 6.1.167 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.130 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.78 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.20 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.10 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0-rc5 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/4c6aa008b913e808c4f4d3cde36cb1d9bb5967c6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/dbdfaae9609629a9569362e3b8f33d0a20fd783c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ec8bf0571b142f29dc0b68ae2ac3952f7a464b38 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/aa0574182c46963c3cdb8cde46ec93aca21100d8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/224f4678812e1a7bc8341bcb666773a0aec5ea6f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/3932620c04c2938c93c0890c225960d3d34ba355 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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