{"id":"CVE-2025-38614","title":"eventpoll: Fix semi-unbounded recursion","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\neventpoll: Fix semi-unbounded recursion\n\nEnsure that epoll instances can never form a graph deeper than\nEP_MAX_NESTS+1 links.\n\nCurrently, ep_loop_check_proc() ensures t…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e < 71379495ab70eaba19224bd71b5b9b399eb85e04","Linux >= 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e < 1b13b033062824495554e836a1ff5f85ccf6b039","Linux >= 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e < 2a0c0c974bea9619c6f41794775ae4b97530e0e6","Linux >= 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e < 7a2125962c42d5336ca0495a9ce4cb38a63e9161","Linux >= 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e < ea5f97dbdcb1651581a22bd10afd2f0dd9dc11d6","Linux >= 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e < 3542c90797bc3ab83ebab54b737d751cf3682036","Linux >= 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e < f2e467a48287c868818085aa35389a224d226732","Linux 8216e1a0d47cae06a75c42346f19dffe14e42d57","Linux 28a92748aa4bc57d35e7b079498b0ac2e7610a37","Linux 7eebcd4792c5a341559aed327b6afecbb1c46402","Linux 0eccd188cfeaf857a26f2d72941d27d298cf6a54","Linux a72affdbb09f3f24f64ffcbbdf62c2e57c58f379","Linux >= 2.6.32.30 < 2.6.33","Linux >= 2.6.33.8 < 2.6.34","Linux >= 2.6.34.10 < 2.6.35","Linux >= 2.6.35.12 < 2.6.36","Linux >= 2.6.37.3 < 2.6.38","Linux 2.6.38"],"published":"2025-08-19","updated":"2026-09-08","sourceUpdated":"2026-09-08T08:41:53.814Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2025-38614","references":[{"url":"https://git.kernel.org/stable/c/71379495ab70eaba19224bd71b5b9b399eb85e04"},{"url":"https://git.kernel.org/stable/c/1b13b033062824495554e836a1ff5f85ccf6b039"},{"url":"https://git.kernel.org/stable/c/2a0c0c974bea9619c6f41794775ae4b97530e0e6"},{"url":"https://git.kernel.org/stable/c/7a2125962c42d5336ca0495a9ce4cb38a63e9161"},{"url":"https://git.kernel.org/stable/c/ea5f97dbdcb1651581a22bd10afd2f0dd9dc11d6"},{"url":"https://git.kernel.org/stable/c/3542c90797bc3ab83ebab54b737d751cf3682036"},{"url":"https://git.kernel.org/stable/c/f2e467a48287c868818085aa35389a224d226732"}],"tags":["cve.org"],"epss":0.00177,"epssPercentile":0.07544,"ingestedAt":"2026-09-08T15:33:26.997Z","slug":"CVE-2025-38614","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\neventpoll: Fix semi-unbounded recursion\n\nEnsure that epoll instances can never form a graph deeper than\nEP_MAX_NESTS+1 links.\n\nCurrently, ep_loop_check_proc() ensures that the graph is loop-free and\ndoes some recursion depth checks, but those recursion depth checks don't\nlimit the depth of the resulting tree for two reasons:\n\n - They don't look upwards in the tree.\n - If there are multiple downwards paths of different lengths, only one of\n   the paths is actually considered for the depth check since commit\n   28d82dc1c4ed (\"epoll: limit paths\").\n\nEssentially, the current recursion depth check in ep_loop_check_proc() just\nserves to prevent it from recursing too deeply while checking for loops.\n\nA more thorough check is done in reverse_path_check() after the new graph\nedge has already been created; this checks, among other things, that no\npaths going upwards from any non-epoll file with a length of more than 5\nedges exist. However, this check does not apply to non-epoll files.\n\nAs a result, it is possible to recurse to a depth of at least roughly 500,\ntested on v6.15. (I am unsure if deeper recursion is possible; and this may\nhave changed with commit 8c44dac8add7 (\"eventpoll: Fix priority inversion\nproblem\").)\n\nTo fix it:\n\n1. In ep_loop_check_proc(), note the subtree depth of each visited node,\nand use subtree depths for the total depth calculation even when a subtree\nhas already been visited.\n2. Add ep_get_upwards_depth_proc() for similarly determining the maximum\ndepth of an upwards walk.\n3. In ep_loop_check(), use these values to limit the total path length\nbetween epoll nodes to EP_MAX_NESTS edges.\n\n## Affected\n\n- `Linux >= 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e < 71379495ab70eaba19224bd71b5b9b399eb85e04`\n- `Linux >= 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e < 1b13b033062824495554e836a1ff5f85ccf6b039`\n- `Linux >= 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e < 2a0c0c974bea9619c6f41794775ae4b97530e0e6`\n- `Linux >= 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e < 7a2125962c42d5336ca0495a9ce4cb38a63e9161`\n- `Linux >= 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e < ea5f97dbdcb1651581a22bd10afd2f0dd9dc11d6`\n- `Linux >= 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e < 3542c90797bc3ab83ebab54b737d751cf3682036`\n- `Linux >= 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e < f2e467a48287c868818085aa35389a224d226732`\n- `Linux 8216e1a0d47cae06a75c42346f19dffe14e42d57`\n- `Linux 28a92748aa4bc57d35e7b079498b0ac2e7610a37`\n- `Linux 7eebcd4792c5a341559aed327b6afecbb1c46402`\n- `Linux 0eccd188cfeaf857a26f2d72941d27d298cf6a54`\n- `Linux a72affdbb09f3f24f64ffcbbdf62c2e57c58f379`\n- `Linux >= 2.6.32.30 < 2.6.33`\n- `Linux >= 2.6.33.8 < 2.6.34`\n- `Linux >= 2.6.34.10 < 2.6.35`\n- `Linux >= 2.6.35.12 < 2.6.36`\n- `Linux >= 2.6.37.3 < 2.6.38`\n- `Linux 2.6.38`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}