{"id":"CVE-2026-23319","revision":"0c59028ad0664b3ea1cc0b25b44b7738","records":[{"revision":"0c59028ad0664b3ea1cc0b25b44b7738","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-23319","aliases":[],"title":"bpf: Fix a UAF issue in bpf_trampoline_link_cgroup_shim","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix a UAF issue in bpf_trampoline_link_cgroup_shim\n\nThe root cause of this bug is that when 'bpf_link_put' reduces the\nrefcount of 'shim_link->link.link' to zero, the resource is considered\nreleased but may still be referenced via 'tr->progs_hlist' in\n'cgroup_shim_find'. The actual cleanup of 'tr->progs_hlist' in\n'bpf_shim_tramp_link_release' is deferred. During this window, another\nprocess can cause a use-after-free via 'bpf_trampoline_link_cgroup_shim'.\n\nBased on Martin KaFai Lau's suggestions, I have created a simple patch.\n\nTo fix this:\n   Add an atomic non-zero check in 'bpf_trampoline_link_cgroup_shim'.\n   Only increment the refcount if it is not already zero.\n\nTesting:\n   I verified the fix by adding a delay in\n   'bpf_shim_tramp_link_release' to make the bug easier to trigger:\n\nstatic void bpf_shim_tramp_link_release(struct bpf_link *link)\n{\n\t/* ... */\n\tif (!shim_link->trampoline)\n\t\treturn;\n\n+\tmsleep(100);\n\tWARN_ON_ONCE(bpf_trampoline_unlink_prog(&shim_link->link,\n\t\tshim_link->trampoline, NULL));\n\tbpf_trampoline_put(shim_link->trampoline);\n}\n\nBefore the patch, running a PoC easily reproduced the crash(almost 100%)\nwith a call trace similar to KaiyanM's report.\nAfter the patch, the bug no longer occurs even after millions of\niterations.","state":0,"publishedAt":"2026-03-25T10:27:13.678+00:00","modifiedAt":"2026-10-15T01:14:02.294+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"kernel/bpf/trampoline.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e\",\n                            \"lessThan\": \"529e685e522b9d7fb379dbe6929dcdf520e34c8c\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e\",\n                            \"lessThan\": \"9b02c5c4147f8af8ed783c8deb5df927a55c3951\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e\",\n                            \"lessThan\": \"cfcfa0ca0212162aa472551266038e8fd6768cff\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e\",\n                            \"lessThan\": \"3eeddb80191f7626ec1ef742bfff51ec3b0fa5c2\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e\",\n                            \"lessThan\": \"4e8a0005d633a4adc98e3b65d5080f93b90d356b\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e\",\n                            \"lessThan\": \"56145d237385ca0e7ca9ff7b226aaf2eb8ef368b\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"kernel/bpf/trampoline.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"6.0\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"6.0\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.167\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.130\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.77\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.17\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.19.7\",\n                            \"lessThanOrEqual\": \"6.19.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.0\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/529e685e522b9d7fb379dbe6929dcdf520e34c8c","https://git.kernel.org/stable/c/9b02c5c4147f8af8ed783c8deb5df927a55c3951","https://git.kernel.org/stable/c/cfcfa0ca0212162aa472551266038e8fd6768cff","https://git.kernel.org/stable/c/3eeddb80191f7626ec1ef742bfff51ec3b0fa5c2","https://git.kernel.org/stable/c/4e8a0005d633a4adc98e3b65d5080f93b90d356b","https://git.kernel.org/stable/c/56145d237385ca0e7ca9ff7b226aaf2eb8ef368b"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-23319","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-23319","identifiers":["CVE-2026-23319"]},"retained":false,"historicalAffected":[]}],"coverage":[]}