{"id":"CVE-2026-90392","state":"PUBLISHED","title":"bpf: Fix potential UAF when reading bpf link info","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix potential UAF when reading bpf link info\n\nIn bpf_link_show_fdinfo and bpf_link_get_info_by_fd, link->prog is\naccessed without holding any locks. If the prog is concurrently replaced\nvia bpf_link_update, the old prog can be freed, leading to a potential\nUAF issue.\n\nFix this by accessing link->prog under RCU protection to safely fetch\nthe pointer and guarantee its lifetime while reading its fields.","publishedAt":"2026-09-17T16:09:25.738Z","updatedAt":"2026-10-30T12:35:28.141Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"0c991ebc8c69d29b7fc44db17075c5aa5253e2ab","status":"affected","lessThan":"4c8432a332d4a24dc2742f56062a53d8fad36f53","versionType":"git"},{"version":"0c991ebc8c69d29b7fc44db17075c5aa5253e2ab","status":"affected","lessThan":"a5c936ac904767fc1d943d40b0308bcb2ae2509b","versionType":"git"},{"version":"0c991ebc8c69d29b7fc44db17075c5aa5253e2ab","status":"affected","lessThan":"d7d7208e2603b45724b684f4df73904fb347741e","versionType":"git"},{"version":"0c991ebc8c69d29b7fc44db17075c5aa5253e2ab","status":"affected","lessThan":"85cf991c881e7198be32be05a9daa2625390c8b3","versionType":"git"},{"version":"0c991ebc8c69d29b7fc44db17075c5aa5253e2ab","status":"affected","lessThan":"79347e42cfbc9e78872922e8f08a70609c9af82f","versionType":"git"},{"version":"0c991ebc8c69d29b7fc44db17075c5aa5253e2ab","status":"affected","lessThan":"863f3ddd0b8ac65abfb50d3be0869268ac0e277b","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/syscall.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.7","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.7","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.52","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/syscall.c"]}],"references":["https://git.kernel.org/stable/c/4c8432a332d4a24dc2742f56062a53d8fad36f53","https://git.kernel.org/stable/c/a5c936ac904767fc1d943d40b0308bcb2ae2509b","https://git.kernel.org/stable/c/d7d7208e2603b45724b684f4df73904fb347741e","https://git.kernel.org/stable/c/85cf991c881e7198be32be05a9daa2625390c8b3","https://git.kernel.org/stable/c/79347e42cfbc9e78872922e8f08a70609c9af82f","https://git.kernel.org/stable/c/863f3ddd0b8ac65abfb50d3be0869268ac0e277b"],"weaknesses":[],"ingestedAt":"2026-10-30T12:54:04.478Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/90xxx/CVE-2026-90392.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-90392","state":"PUBLISHED","datePublished":"2026-09-17T16:09:25.738Z","dateUpdated":"2026-10-30T12:35:28.141Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.810Z"},"containers":{"cna":{"title":"bpf: Fix potential UAF when reading bpf link info","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix potential UAF when reading bpf link info\n\nIn bpf_link_show_fdinfo and bpf_link_get_info_by_fd, link->prog is\naccessed without holding any locks. If the prog is concurrently replaced\nvia bpf_link_update, the old prog can be freed, leading to a potential\nUAF issue.\n\nFix this by accessing link->prog under RCU protection to safely fetch\nthe pointer and guarantee its lifetime while reading its fields."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"0c991ebc8c69d29b7fc44db17075c5aa5253e2ab","status":"affected","lessThan":"4c8432a332d4a24dc2742f56062a53d8fad36f53","versionType":"git"},{"version":"0c991ebc8c69d29b7fc44db17075c5aa5253e2ab","status":"affected","lessThan":"a5c936ac904767fc1d943d40b0308bcb2ae2509b","versionType":"git"},{"version":"0c991ebc8c69d29b7fc44db17075c5aa5253e2ab","status":"affected","lessThan":"d7d7208e2603b45724b684f4df73904fb347741e","versionType":"git"},{"version":"0c991ebc8c69d29b7fc44db17075c5aa5253e2ab","status":"affected","lessThan":"85cf991c881e7198be32be05a9daa2625390c8b3","versionType":"git"},{"version":"0c991ebc8c69d29b7fc44db17075c5aa5253e2ab","status":"affected","lessThan":"79347e42cfbc9e78872922e8f08a70609c9af82f","versionType":"git"},{"version":"0c991ebc8c69d29b7fc44db17075c5aa5253e2ab","status":"affected","lessThan":"863f3ddd0b8ac65abfb50d3be0869268ac0e277b","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/syscall.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.7","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.7","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.52","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/syscall.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/4c8432a332d4a24dc2742f56062a53d8fad36f53"},{"url":"https://git.kernel.org/stable/c/a5c936ac904767fc1d943d40b0308bcb2ae2509b"},{"url":"https://git.kernel.org/stable/c/d7d7208e2603b45724b684f4df73904fb347741e"},{"url":"https://git.kernel.org/stable/c/85cf991c881e7198be32be05a9daa2625390c8b3"},{"url":"https://git.kernel.org/stable/c/79347e42cfbc9e78872922e8f08a70609c9af82f"},{"url":"https://git.kernel.org/stable/c/863f3ddd0b8ac65abfb50d3be0869268ac0e277b"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The dangling link->prog is read from the local bpf(2) BPF_OBJ_GET_INFO_BY_FD command (bpf_obj_get_info_by_fd()->bpf_link_get_info_by_fd()) or from bpf_link_show_fdinfo() when reading /proc/self/fdinfo on a bpf_link fd; neither path takes the malformed state from a network protocol.\nAC:L - The attacker owns both sides: one thread issues BPF_LINK_UPDATE so link_update() runs cgroup_bpf_replace()/tcx_link_update()/sock_map_link_update_prog() which xchg(&link->prog) and bpf_prog_put() the old program, while another thread they control races bpf_link_get_info_by_fd() or bpf_link_show_fdinfo(), which sleeps in seq_printf after capturing the pointer.\nPR:L - Creating a replaceable link requires bpf_prog_load() of a type whose ops implement update_prog (CGROUP_SKB, SCHED_CLS, SK_SKB, XDP, FLOW_DISSECTOR) plus BPF_LINK_CREATE; those paths require bpf_token_capable(CAP_BPF) and usually CAP_NET_ADMIN (CGROUP_SKB attach also checks it in bpf_prog_attach_check_attach_type), which a BPF token delegates into a user namespace.\nUI:N - The attacker loads two programs, BPF_LINK_CREATE the first as a cgroup/tcx/sockmap/xdp/netns link, closes the old program fd so the link holds the last ref, then races BPF_LINK_UPDATE against BPF_OBJ_GET_INFO_BY_FD or fdinfo in their own process; no other user action is required.\nS:U - The use-after-free is of the replaced bpf_prog inside bpf_link_get_info_by_fd()/bpf_link_show_fdinfo() on the host kernel; impact is local kernel memory corruption and privilege escalation, not a VM, IOMMU, or other authority-boundary cross.\nC:H - After the concurrent bpf_prog_put(), bpf_link_get_info_by_fd() reads prog->aux->id and bpf_link_show_fdinfo() copies prog->tag then aux->id from the freed bpf_prog; __bpf_prog_free() kfree()s the kmalloc bpf_prog_aux, so reclaiming that object turns the dangling aux pointer into an arbitrary kernel read.\nI:H - The same bpf_prog/bpf_prog_aux use-after-free after cgroup_bpf_replace() (or tcx/sockmap/xdp/netns update_prog) lets the attacker spray the freed kmalloc aux and vmalloc prog; kernel heap UAF of those objects yields write and control-flow hijack primitives.\nA:H - bpf_link_get_info_by_fd() and bpf_link_show_fdinfo() dereference the freed bpf_prog and prog->aux after BPF_LINK_UPDATE drops the last ref via bpf_prog_put(); a recycled or poisoned aux pointer causes a kernel oops."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:35:28.141Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.6.157"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.12.110"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.18.52"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"7.2.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}