{"id":"CVE-2026-68186","title":"binfmt_misc: set have_execfd only once the interpreter is opened","summary":"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->have_execfd as soon as it sees the 'O'\n(or 'C') flag. This happens wel…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 < a8e9e9450df44e9dd529ec5beff283f48f4f4b97","Linux >= bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 < a261dc49d99681c9c71f38d16e31812dc3e30412","Linux >= bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 < 40c09b7a1d4e0a4866042c87c2bd911bb57566c8","Linux >= bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 < 0f19d54e2524f0bf183b82f365ae4e49b4a2f788","Linux >= bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 < 2dd0298905e97795a9c5ec30cf5b41975f821632","Linux >= bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 < 1cd4e9b7967dab48c9f79a00b06ffff7208c0993","Linux >= bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 < 5ccc99d58f94fad258c9c375715b3974e48620e8","Linux >= bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 < bbf5f639918dc011aaf60aab8480218758ee68c5","Linux 5.8"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-06T16:43:58.814480Z"},"published":"2026-08-10","updated":"2026-11-06","sourceUpdated":"2026-11-06T16:45:00.927Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-68186","references":[{"url":"https://git.kernel.org/stable/c/a8e9e9450df44e9dd529ec5beff283f48f4f4b97"},{"url":"https://git.kernel.org/stable/c/a261dc49d99681c9c71f38d16e31812dc3e30412"},{"url":"https://git.kernel.org/stable/c/40c09b7a1d4e0a4866042c87c2bd911bb57566c8"},{"url":"https://git.kernel.org/stable/c/0f19d54e2524f0bf183b82f365ae4e49b4a2f788"},{"url":"https://git.kernel.org/stable/c/2dd0298905e97795a9c5ec30cf5b41975f821632"},{"url":"https://git.kernel.org/stable/c/1cd4e9b7967dab48c9f79a00b06ffff7208c0993"},{"url":"https://git.kernel.org/stable/c/5ccc99d58f94fad258c9c375715b3974e48620e8"},{"url":"https://git.kernel.org/stable/c/bbf5f639918dc011aaf60aab8480218758ee68c5"}],"tags":["cve.org"],"epss":0.00216,"epssPercentile":0.12155,"ingestedAt":"2026-11-06T16:57:43.138Z","slug":"CVE-2026-68186","body":"## Overview\n\nIn 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->have_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->executable 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->executable);\n\nand NULL derefs. Had it not, the hand-off later in the same function\nwould have failed anyway. FD_ADD(0, bprm->executable) 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.\n\n## Affected\n\n- `Linux >= bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 < a8e9e9450df44e9dd529ec5beff283f48f4f4b97`\n- `Linux >= bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 < a261dc49d99681c9c71f38d16e31812dc3e30412`\n- `Linux >= bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 < 40c09b7a1d4e0a4866042c87c2bd911bb57566c8`\n- `Linux >= bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 < 0f19d54e2524f0bf183b82f365ae4e49b4a2f788`\n- `Linux >= bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 < 2dd0298905e97795a9c5ec30cf5b41975f821632`\n- `Linux >= bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 < 1cd4e9b7967dab48c9f79a00b06ffff7208c0993`\n- `Linux >= bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 < 5ccc99d58f94fad258c9c375715b3974e48620e8`\n- `Linux >= bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 < bbf5f639918dc011aaf60aab8480218758ee68c5`\n- `Linux 5.8`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}