{"id":"CVE-2026-53070","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-53070","generatedAt":"2026-10-28T09:27:40.177Z","title":"In the Linux kernel, the following vulnerability has been resolved: sctp: disable BH before calling udp_tunnel_xmit_skb() udp_tunnel_xmit_skb() / udp_tunnel6_xmit_skb() are expected to run with BH disabled.","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: disable BH before calling udp_tunnel_xmit_skb()\n\nudp_tunnel_xmit_skb() / udp_tunnel6_xmit_skb() are expected to run with\nBH disabled.  After commit 6f1a9140ecda (\"add xmit recursion limit to\ntunnel xmit functions\"), on the path:\n\n  udp(6)_tunnel_xmit_skb() -> ip(6)tunnel_xmit()\n\ndev_xmit_recursion_inc()/dec() must stay balanced on the same CPU.\n\nWithout local_bh_disable(), the context may move between CPUs, which can\nbreak the inc/dec pairing. This may lead to incorrect recursion level\ndetection and cause packets to be dropped in ip(6)_tunnel_xmit() or\n__dev_queue_xmit().\n\nFix it by disabling BH around both IPv4 and IPv6 SCTP UDP xmit paths.\n\nIn my testing, after enabling the SCTP over UDP:\n\n  # ip net exec ha sysctl -w net.sctp.udp_port=9899\n  # ip net exec ha sysctl -w net.sctp.encap_port=9899\n  # ip net exec hb sysctl -w net.sctp.udp_port=9899\n  # ip net exec hb sysctl -w net.sctp.encap_port=9899\n\n  # ip net exec ha iperf3 -s\n\n- without this patch:\n\n  # ip net exec hb iperf3 -c 192.168.0.1 --sctp\n  [  5]   0.00-10.00  sec  37.2 MBytes  31.2 Mbits/sec  sender\n  [  5]   0.00-10.00  sec  37.1 MBytes  31.1 Mbits/sec  receiver\n\n- with this patch:\n\n  # ip net exec hb iperf3 -c 192.168.0.1 --sctp\n  [  5]   0.00-10.00  sec  3.14 GBytes  2.69 Gbits/sec  sender\n  [  5]   0.00-10.00  sec  3.14 GBytes  2.69 Gbits/sec  receiver","published":"2026-06-24T17:17:21.000Z","lastModified":"2026-10-21T13:19:10.000Z","status":"Modified","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":{"version":"3.1","score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"cwe":["CWE-362"],"affected":["linux/linux kernel"],"epss":{"score":0.00276,"percentile":0.19909,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.28%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://git.kernel.org/stable/c/0de7db2eb27e82b983157016fa604b1ba664ae5f","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/2cd7e6971fc2787408ceef17906ea152791448cf","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/790093245e35040c2adb15f48970020425aa3f47","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/7f0062c40781fe0a340965f5bb0816681982ff4c","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/be3bfcb34bda04f6a350710db471d4133f950f2c","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-53070","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}