CVE-2026-23276 (GCVE-0-2026-23276)
Vulnerability from cvelistv5
Published
2026-03-20 08:08
Modified
2026-04-13 06:03
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
net: add xmit recursion limit to tunnel xmit functions
Tunnel xmit functions (iptunnel_xmit, ip6tunnel_xmit) lack their own
recursion limit. When a bond device in broadcast mode has GRE tap
interfaces as slaves, and those GRE tunnels route back through the
bond, multicast/broadcast traffic triggers infinite recursion between
bond_xmit_broadcast() and ip_tunnel_xmit()/ip6_tnl_xmit(), causing
kernel stack overflow.
The existing XMIT_RECURSION_LIMIT (8) in the no-qdisc path is not
sufficient because tunnel recursion involves route lookups and full IP
output, consuming much more stack per level. Use a lower limit of 4
(IP_TUNNEL_RECURSION_LIMIT) to prevent overflow.
Add recursion detection using dev_xmit_recursion helpers directly in
iptunnel_xmit() and ip6tunnel_xmit() to cover all IPv4/IPv6 tunnel
paths including UDP encapsulated tunnels (VXLAN, Geneve, etc.).
Move dev_xmit_recursion helpers from net/core/dev.h to public header
include/linux/netdevice.h so they can be used by tunnel code.
BUG: KASAN: stack-out-of-bounds in blake2s.constprop.0+0xe7/0x160
Write of size 32 at addr ffff88810033fed0 by task kworker/0:1/11
Workqueue: mld mld_ifc_work
Call Trace:
<TASK>
__build_flow_key.constprop.0 (net/ipv4/route.c:515)
ip_rt_update_pmtu (net/ipv4/route.c:1073)
iptunnel_xmit (net/ipv4/ip_tunnel_core.c:84)
ip_tunnel_xmit (net/ipv4/ip_tunnel.c:847)
gre_tap_xmit (net/ipv4/ip_gre.c:779)
dev_hard_start_xmit (net/core/dev.c:3887)
sch_direct_xmit (net/sched/sch_generic.c:347)
__dev_queue_xmit (net/core/dev.c:4802)
bond_dev_queue_xmit (drivers/net/bonding/bond_main.c:312)
bond_xmit_broadcast (drivers/net/bonding/bond_main.c:5279)
bond_start_xmit (drivers/net/bonding/bond_main.c:5530)
dev_hard_start_xmit (net/core/dev.c:3887)
__dev_queue_xmit (net/core/dev.c:4841)
ip_finish_output2 (net/ipv4/ip_output.c:237)
ip_output (net/ipv4/ip_output.c:438)
iptunnel_xmit (net/ipv4/ip_tunnel_core.c:86)
gre_tap_xmit (net/ipv4/ip_gre.c:779)
dev_hard_start_xmit (net/core/dev.c:3887)
sch_direct_xmit (net/sched/sch_generic.c:347)
__dev_queue_xmit (net/core/dev.c:4802)
bond_dev_queue_xmit (drivers/net/bonding/bond_main.c:312)
bond_xmit_broadcast (drivers/net/bonding/bond_main.c:5279)
bond_start_xmit (drivers/net/bonding/bond_main.c:5530)
dev_hard_start_xmit (net/core/dev.c:3887)
__dev_queue_xmit (net/core/dev.c:4841)
ip_finish_output2 (net/ipv4/ip_output.c:237)
ip_output (net/ipv4/ip_output.c:438)
iptunnel_xmit (net/ipv4/ip_tunnel_core.c:86)
ip_tunnel_xmit (net/ipv4/ip_tunnel.c:847)
gre_tap_xmit (net/ipv4/ip_gre.c:779)
dev_hard_start_xmit (net/core/dev.c:3887)
sch_direct_xmit (net/sched/sch_generic.c:347)
__dev_queue_xmit (net/core/dev.c:4802)
bond_dev_queue_xmit (drivers/net/bonding/bond_main.c:312)
bond_xmit_broadcast (drivers/net/bonding/bond_main.c:5279)
bond_start_xmit (drivers/net/bonding/bond_main.c:5530)
dev_hard_start_xmit (net/core/dev.c:3887)
__dev_queue_xmit (net/core/dev.c:4841)
mld_sendpack
mld_ifc_work
process_one_work
worker_thread
</TASK>
References
| URL | Tags | |
|---|---|---|
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"include/linux/netdevice.h",
"include/net/ip6_tunnel.h",
"include/net/ip_tunnels.h",
"net/core/dev.h",
"net/ipv4/ip_tunnel_core.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "834c4f645726a25fd71ea50cdfb5c135f8f95d85",
"status": "affected",
"version": "745e20f1b626b1be4b100af5d4bf7b3439392f8f",
"versionType": "git"
},
{
"lessThan": "8a57deeb256069f262957d8012418559ff66c385",
"status": "affected",
"version": "745e20f1b626b1be4b100af5d4bf7b3439392f8f",
"versionType": "git"
},
{
"lessThan": "b56b8d19bd05e2a8338385c770bc2b60590bc81e",
"status": "affected",
"version": "745e20f1b626b1be4b100af5d4bf7b3439392f8f",
"versionType": "git"
},
{
"lessThan": "6f1a9140ecda3baba3d945b9a6155af4268aafc4",
"status": "affected",
"version": "745e20f1b626b1be4b100af5d4bf7b3439392f8f",
"versionType": "git"
},
{
"status": "affected",
"version": "3f266b04185de51d8e6446eb1fccec3b5e7ce575",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"include/linux/netdevice.h",
"include/net/ip6_tunnel.h",
"include/net/ip_tunnels.h",
"net/core/dev.h",
"net/ipv4/ip_tunnel_core.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.37"
},
{
"lessThan": "2.6.37",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.78",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.19",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.19.*",
"status": "unaffected",
"version": "6.19.9",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.0",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.78",
"versionStartIncluding": "2.6.37",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.19",
"versionStartIncluding": "2.6.37",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.19.9",
"versionStartIncluding": "2.6.37",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.0",
"versionStartIncluding": "2.6.37",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "2.6.35.9",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: add xmit recursion limit to tunnel xmit functions\n\nTunnel xmit functions (iptunnel_xmit, ip6tunnel_xmit) lack their own\nrecursion limit. When a bond device in broadcast mode has GRE tap\ninterfaces as slaves, and those GRE tunnels route back through the\nbond, multicast/broadcast traffic triggers infinite recursion between\nbond_xmit_broadcast() and ip_tunnel_xmit()/ip6_tnl_xmit(), causing\nkernel stack overflow.\n\nThe existing XMIT_RECURSION_LIMIT (8) in the no-qdisc path is not\nsufficient because tunnel recursion involves route lookups and full IP\noutput, consuming much more stack per level. Use a lower limit of 4\n(IP_TUNNEL_RECURSION_LIMIT) to prevent overflow.\n\nAdd recursion detection using dev_xmit_recursion helpers directly in\niptunnel_xmit() and ip6tunnel_xmit() to cover all IPv4/IPv6 tunnel\npaths including UDP encapsulated tunnels (VXLAN, Geneve, etc.).\n\nMove dev_xmit_recursion helpers from net/core/dev.h to public header\ninclude/linux/netdevice.h so they can be used by tunnel code.\n\n BUG: KASAN: stack-out-of-bounds in blake2s.constprop.0+0xe7/0x160\n Write of size 32 at addr ffff88810033fed0 by task kworker/0:1/11\n Workqueue: mld mld_ifc_work\n Call Trace:\n \u003cTASK\u003e\n __build_flow_key.constprop.0 (net/ipv4/route.c:515)\n ip_rt_update_pmtu (net/ipv4/route.c:1073)\n iptunnel_xmit (net/ipv4/ip_tunnel_core.c:84)\n ip_tunnel_xmit (net/ipv4/ip_tunnel.c:847)\n gre_tap_xmit (net/ipv4/ip_gre.c:779)\n dev_hard_start_xmit (net/core/dev.c:3887)\n sch_direct_xmit (net/sched/sch_generic.c:347)\n __dev_queue_xmit (net/core/dev.c:4802)\n bond_dev_queue_xmit (drivers/net/bonding/bond_main.c:312)\n bond_xmit_broadcast (drivers/net/bonding/bond_main.c:5279)\n bond_start_xmit (drivers/net/bonding/bond_main.c:5530)\n dev_hard_start_xmit (net/core/dev.c:3887)\n __dev_queue_xmit (net/core/dev.c:4841)\n ip_finish_output2 (net/ipv4/ip_output.c:237)\n ip_output (net/ipv4/ip_output.c:438)\n iptunnel_xmit (net/ipv4/ip_tunnel_core.c:86)\n gre_tap_xmit (net/ipv4/ip_gre.c:779)\n dev_hard_start_xmit (net/core/dev.c:3887)\n sch_direct_xmit (net/sched/sch_generic.c:347)\n __dev_queue_xmit (net/core/dev.c:4802)\n bond_dev_queue_xmit (drivers/net/bonding/bond_main.c:312)\n bond_xmit_broadcast (drivers/net/bonding/bond_main.c:5279)\n bond_start_xmit (drivers/net/bonding/bond_main.c:5530)\n dev_hard_start_xmit (net/core/dev.c:3887)\n __dev_queue_xmit (net/core/dev.c:4841)\n ip_finish_output2 (net/ipv4/ip_output.c:237)\n ip_output (net/ipv4/ip_output.c:438)\n iptunnel_xmit (net/ipv4/ip_tunnel_core.c:86)\n ip_tunnel_xmit (net/ipv4/ip_tunnel.c:847)\n gre_tap_xmit (net/ipv4/ip_gre.c:779)\n dev_hard_start_xmit (net/core/dev.c:3887)\n sch_direct_xmit (net/sched/sch_generic.c:347)\n __dev_queue_xmit (net/core/dev.c:4802)\n bond_dev_queue_xmit (drivers/net/bonding/bond_main.c:312)\n bond_xmit_broadcast (drivers/net/bonding/bond_main.c:5279)\n bond_start_xmit (drivers/net/bonding/bond_main.c:5530)\n dev_hard_start_xmit (net/core/dev.c:3887)\n __dev_queue_xmit (net/core/dev.c:4841)\n mld_sendpack\n mld_ifc_work\n process_one_work\n worker_thread\n \u003c/TASK\u003e"
}
],
"providerMetadata": {
"dateUpdated": "2026-04-13T06:03:26.006Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/834c4f645726a25fd71ea50cdfb5c135f8f95d85"
},
{
"url": "https://git.kernel.org/stable/c/8a57deeb256069f262957d8012418559ff66c385"
},
{
"url": "https://git.kernel.org/stable/c/b56b8d19bd05e2a8338385c770bc2b60590bc81e"
},
{
"url": "https://git.kernel.org/stable/c/6f1a9140ecda3baba3d945b9a6155af4268aafc4"
}
],
"title": "net: add xmit recursion limit to tunnel xmit functions",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-23276",
"datePublished": "2026-03-20T08:08:56.575Z",
"dateReserved": "2026-01-13T15:37:45.991Z",
"dateUpdated": "2026-04-13T06:03:26.006Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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