{"api_version":"1","generated_at":"2026-05-28T22:09:43+00:00","cve":"CVE-2026-23276","urls":{"html":"https://cve.report/CVE-2026-23276","api":"https://cve.report/api/cve/CVE-2026-23276.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-23276","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-23276"},"summary":{"title":"net: add xmit recursion limit to tunnel xmit functions","description":"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  <TASK>\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  </TASK>","state":"PUBLISHED","assigner":"Linux","published_at":"2026-03-20 09:16:13","updated_at":"2026-03-25 11:16:21"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/b56b8d19bd05e2a8338385c770bc2b60590bc81e","name":"https://git.kernel.org/stable/c/b56b8d19bd05e2a8338385c770bc2b60590bc81e","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/8a57deeb256069f262957d8012418559ff66c385","name":"https://git.kernel.org/stable/c/8a57deeb256069f262957d8012418559ff66c385","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/6f1a9140ecda3baba3d945b9a6155af4268aafc4","name":"https://git.kernel.org/stable/c/6f1a9140ecda3baba3d945b9a6155af4268aafc4","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/834c4f645726a25fd71ea50cdfb5c135f8f95d85","name":"https://git.kernel.org/stable/c/834c4f645726a25fd71ea50cdfb5c135f8f95d85","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-23276","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23276","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 745e20f1b626b1be4b100af5d4bf7b3439392f8f 834c4f645726a25fd71ea50cdfb5c135f8f95d85 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 745e20f1b626b1be4b100af5d4bf7b3439392f8f 8a57deeb256069f262957d8012418559ff66c385 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 745e20f1b626b1be4b100af5d4bf7b3439392f8f b56b8d19bd05e2a8338385c770bc2b60590bc81e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 745e20f1b626b1be4b100af5d4bf7b3439392f8f 6f1a9140ecda3baba3d945b9a6155af4268aafc4 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3f266b04185de51d8e6446eb1fccec3b5e7ce575 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2.6.37","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 2.6.37 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.78 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.19 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.19.9 6.19.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"23276","cve":"CVE-2026-23276","epss":"0.000210000","percentile":"0.062860000","score_date":"2026-05-27","updated_at":"2026-05-28 00:02:13"},"legacy_qids":[]},"source_records":{"cve_program":{"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  <TASK>\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  </TASK>"}],"providerMetadata":{"dateUpdated":"2026-05-11T22:03:44.045Z","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":"2026-05-11T22:03:44.045Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-03-20 09:16:13","lastModifiedDate":"2026-03-25 11:16:21","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"23276","Ordinal":"1","Title":"net: add xmit recursion limit to tunnel xmit functions","CVE":"CVE-2026-23276","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"23276","Ordinal":"1","NoteData":"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  <TASK>\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  </TASK>","Type":"Description","Title":"net: add xmit recursion limit to tunnel xmit functions"}]}}}