FKIE_CVE-2026-23397
Vulnerability from fkie_nvd - Published: 2026-03-26 11:16 - Updated: 2026-03-30 13:26
Severity ?
Summary
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.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfnetlink_osf: validate individual option lengths in fingerprints\n\nnfnl_osf_add_callback() validates opt_num bounds and string\nNUL-termination but does not check individual option length fields.\nA zero-length option causes nf_osf_match_one() to enter the option\nmatching loop even when foptsize sums to zero, which matches packets\nwith no TCP options where ctx-\u003eoptp is NULL:\n\n Oops: general protection fault\n KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\n RIP: 0010:nf_osf_match_one (net/netfilter/nfnetlink_osf.c:98)\n Call Trace:\n nf_osf_match (net/netfilter/nfnetlink_osf.c:227)\n xt_osf_match_packet (net/netfilter/xt_osf.c:32)\n ipt_do_table (net/ipv4/netfilter/ip_tables.c:293)\n nf_hook_slow (net/netfilter/core.c:623)\n ip_local_deliver (net/ipv4/ip_input.c:262)\n ip_rcv (net/ipv4/ip_input.c:573)\n\nAdditionally, an MSS option (kind=2) with length \u003c 4 causes\nout-of-bounds reads when nf_osf_match_one() unconditionally accesses\noptp[2] and optp[3] for MSS value extraction. While RFC 9293\nsection 3.2 specifies that the MSS option is always exactly 4\nbytes (Kind=2, Length=4), the check uses \"\u003c 4\" rather than\n\"!= 4\" because lengths greater than 4 do not cause memory\nsafety issues -- the buffer is guaranteed to be at least\nfoptsize bytes by the ctx-\u003eoptsize == foptsize check.\n\nReject fingerprints where any option has zero length, or where an MSS\noption has length less than 4, at add time rather than trusting these\nvalues in the packet matching hot path."
},
{
"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nnfnetlink_osf: validar longitudes de opciones individuales en huellas digitales\n\nnfnl_osf_add_callback() valida los l\u00edmites de opt_num y la terminaci\u00f3n NUL de cadena, pero no verifica los campos de longitud de opciones individuales. Una opci\u00f3n de longitud cero hace que nf_osf_match_one() entre en el bucle de coincidencia de opciones incluso cuando foptsize suma cero, lo que coincide con paquetes sin opciones TCP donde ctx-\u0026gt;optp es NULL:\n\n Oops: fallo de protecci\u00f3n general\n KASAN: desreferencia de puntero nulo en el rango [0x0000000000000000-0x0000000000000007]\n RIP: 0010:nf_osf_match_one (net/netfilter/nfnetlink_osf.c:98)\n Traza de llamada:\n nf_osf_match (net/netfilter/nfnetlink_osf.c:227)\n xt_osf_match_packet (net/netfilter/xt_osf.c:32)\n ipt_do_table (net/ipv4/netfilter/ip_tables.c:293)\n nf_hook_slow (net/netfilter/core.c:623)\n ip_local_deliver (net/ipv4/ip_input.c:262)\n ip_rcv (net/ipv4/ip_input.c:573)\n\nAdem\u00e1s, una opci\u00f3n MSS (tipo=2) con longitud \u0026lt; 4 causa lecturas fuera de l\u00edmites cuando nf_osf_match_one() accede incondicionalmente a optp[2] y optp[3] para la extracci\u00f3n del valor MSS. Si bien la secci\u00f3n 3.2 de RFC 9293 especifica que la opci\u00f3n MSS es siempre exactamente de 4 bytes (Tipo=2, Longitud=4), la verificaci\u00f3n usa \u0027\u0026lt; 4\u0027 en lugar de \u0027!= 4\u0027 porque las longitudes mayores que 4 no causan problemas de seguridad de la memoria -- el b\u00fafer est\u00e1 garantizado para ser de al menos foptsize bytes por la verificaci\u00f3n ctx-\u0026gt;optsize == foptsize.\n\nRechazar huellas digitales donde cualquier opci\u00f3n tenga longitud cero, o donde una opci\u00f3n MSS tenga longitud menor que 4, en el momento de la adici\u00f3n en lugar de confiar en estos valores en la ruta cr\u00edtica de coincidencia de paquetes."
}
],
"id": "CVE-2026-23397",
"lastModified": "2026-03-30T13:26:50.827",
"metrics": {},
"published": "2026-03-26T11:16:19.720",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/224f4678812e1a7bc8341bcb666773a0aec5ea6f"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/3932620c04c2938c93c0890c225960d3d34ba355"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/4c6aa008b913e808c4f4d3cde36cb1d9bb5967c6"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/aa0574182c46963c3cdb8cde46ec93aca21100d8"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/dbdfaae9609629a9569362e3b8f33d0a20fd783c"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/ec8bf0571b142f29dc0b68ae2ac3952f7a464b38"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Awaiting Analysis"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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