{"id":"CVE-2026-23255","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: add proper RCU protection to /proc/net/ptype\n\nYin Fengwei reported an RCU stall in ptype_seq_show() and provided\na patch.\n\nReal issue is that ptype_seq_next() and …","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: add proper RCU protection to /proc/net/ptype\n\nYin Fengwei reported an RCU stall in ptype_seq_show() and provided\na patch.\n\nReal issue is that ptype_seq_next() and …","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 2.6.12.1, < 6.6.136","linux_kernel >= 6.7, < 6.12.80","linux_kernel >= 6.13, < 6.18.10","linux_kernel = 2.6.12","linux_kernel = 6.19"],"patched":["linux_kernel 6.18.10"],"published":"2026-03-18","updated":"2026-09-08","sourceUpdated":"2026-09-08T09:17:46.567","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-23255","references":[{"url":"https://git.kernel.org/stable/c/002a73470b56848e4c81efeaaedd471e92d66d8d","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/589a530ae44d0c80f523fcfd1a15af8087f27d35","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/dcefd3f0b9ed8288654c75254bdcee8e1085e861","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e974a10a52618f7f57a4bce173a0ed96acd4e5dc","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f613e8b4afea0cd17c7168e8b00e25bc8d33175d","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-019113.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd","cve.org"],"epss":0.00114,"epssPercentile":0.01707,"ingestedAt":"2026-09-08T09:30:07.899Z","slug":"CVE-2026-23255","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnet: add proper RCU protection to /proc/net/ptype\n\nYin Fengwei reported an RCU stall in ptype_seq_show() and provided\na patch.\n\nReal issue is that ptype_seq_next() and ptype_seq_show() violate\nRCU rules.\n\nptype_seq_show() runs under rcu_read_lock(), and reads pt->dev\nto get device name without any barrier.\n\nAt the same time, concurrent writers can remove a packet_type structure\n(which is correctly freed after an RCU grace period) and clear pt->dev\nwithout an RCU grace period.\n\nDefine ptype_iter_state to carry a dev pointer along seq_net_private:\n\nstruct ptype_iter_state {\n\tstruct seq_net_private\tp;\n\tstruct net_device\t*dev; // added in this patch\n};\n\nWe need to record the device pointer in ptype_get_idx() and\nptype_seq_next() so that ptype_seq_show() is safe against\nconcurrent pt->dev changes.\n\nWe also need to add full RCU protection in ptype_seq_next().\n(Missing READ_ONCE() when reading list.next values)\n\nMany thanks to Dong Chenchen for providing a repro.\n\n## Affected\n\n- `linux_kernel >= 2.6.12.1, < 6.6.136`\n- `linux_kernel >= 6.7, < 6.12.80`\n- `linux_kernel >= 6.13, < 6.18.10`\n- `linux_kernel = 2.6.12`\n- `linux_kernel = 6.19`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.18.10`","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}