{"id":"CVE-2026-68186","summary":"binfmt_misc: set have_execfd only once the interpreter is opened","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbinfmt_misc: set have_execfd only once the interpreter is opened\n\nload_misc_binary() raises bprm-\u003ehave_execfd as soon as it sees the 'O'\n(or 'C') flag. This happens well before it opens the interpreter. If\nthat open fails the flag stays set on the bprm. binfmt_misc is at the\nhead of the format list so an interpreter open failure that returns\n-ENOEXEC lets the search fall through to a later format. This means it\nruns the matched binary directly having never staged an interpreter. So\nbprm-\u003eexecutable is NULL while have_execfd falsely claims a descriptor\nis present.\n\nConsequently, begin_new_exec() dereferences the missing executable:\n\n  would_dump(bprm, bprm-\u003eexecutable);\n\nand NULL derefs. Had it not, the hand-off later in the same function\nwould have failed anyway. FD_ADD(0, bprm-\u003eexecutable) rejects a NULL\nfile with -ENOMEM. Both sites are past the point of no return so the\nexec cannot be unwound either way.\n\nThis can be reached by unprivileged users as binfmt_misc can be mounted\nin user namespaces. So a user can register an 'O' entry whose\ninterpreter lives on a FUSE mount, have the FUSE server fail the open\nwith -ENOEXEC and execute a native ELF file that matches the entry.\n\nhave_execfd only means anything alongside the executable it describes\nwhich is not set until the interpreter has been opened and staged.\nSo lets raise it there, next to execfd_creds, which is already set at\nthat point. An open failure now leaves it clear, so the fallback format\nderives credentials from the binary and emits no AT_EXECFD, as it would\nfor any native exec. The argv rewrite load_misc_binary() performs before\nthe open is still not undone. This means the binary sees the interpreter\npath in argv[0] and its own path in argv[1] but that predates this\nchange and only became observable once the exec stopped faulting.","modified":"2026-08-21T03:30:12.671528882Z","published":"2026-08-10T11:59:58.299Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68186.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0f19d54e2524f0bf183b82f365ae4e49b4a2f788"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1cd4e9b7967dab48c9f79a00b06ffff7208c0993"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2dd0298905e97795a9c5ec30cf5b41975f821632"},{"type":"WEB","url":"https://git.kernel.org/stable/c/40c09b7a1d4e0a4866042c87c2bd911bb57566c8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5ccc99d58f94fad258c9c375715b3974e48620e8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a261dc49d99681c9c71f38d16e31812dc3e30412"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a8e9e9450df44e9dd529ec5beff283f48f4f4b97"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bbf5f639918dc011aaf60aab8480218758ee68c5"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68186.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-68186"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"bc2bf338d54b7aadaed49bb45b9e10d4592b2a46"},{"fixed":"a8e9e9450df44e9dd529ec5beff283f48f4f4b97"},{"fixed":"a261dc49d99681c9c71f38d16e31812dc3e30412"},{"fixed":"40c09b7a1d4e0a4866042c87c2bd911bb57566c8"},{"fixed":"0f19d54e2524f0bf183b82f365ae4e49b4a2f788"},{"fixed":"2dd0298905e97795a9c5ec30cf5b41975f821632"},{"fixed":"1cd4e9b7967dab48c9f79a00b06ffff7208c0993"},{"fixed":"5ccc99d58f94fad258c9c375715b3974e48620e8"},{"fixed":"bbf5f639918dc011aaf60aab8480218758ee68c5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-68186.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.8.0"},{"fixed":"5.10.265"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.216"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.183"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.148"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.101"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.42"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-68186.json"}}],"schema_version":"1.9.0"}