binfmt_misc: set have_execfd only once the interpreter is opened

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-68186
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-10 13:20:05 UTC
Updated2026-08-19 17:20:34 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: binfmt_misc: set have_execfd only once the interpreter is opened load_misc_binary() raises bprm->have_execfd as soon as it sees the 'O' (or 'C') flag. This happens well before it opens the interpreter. If that open fails the flag stays set on the bprm. binfmt_misc is at the head of the format list so an interpreter open failure that returns -ENOEXEC lets the search fall through to a later format. This means it runs the matched binary directly having never staged an interpreter. So bprm->executable is NULL while have_execfd falsely claims a descriptor is present. Consequently, begin_new_exec() dereferences the missing executable: would_dump(bprm, bprm->executable); and NULL derefs. Had it not, the hand-off later in the same function would have failed anyway. FD_ADD(0, bprm->executable) rejects a NULL file with -ENOMEM. Both sites are past the point of no return so the exec cannot be unwound either way. This can be reached by unprivileged users as binfmt_misc can be mounted in user namespaces. So a user can register an 'O' entry whose interpreter lives on a FUSE mount, have the FUSE server fail the open with -ENOEXEC and execute a native ELF file that matches the entry. have_execfd only means anything alongside the executable it describes which is not set until the interpreter has been opened and staged. So lets raise it there, next to execfd_creds, which is already set at that point. An open failure now leaves it clear, so the fallback format derives credentials from the binary and emits no AT_EXECFD, as it would for any native exec. The argv rewrite load_misc_binary() performs before the open is still not undone. This means the binary sees the interpreter path in argv[0] and its own path in argv[1] but that predates this change and only became observable once the exec stopped faulting.

Risk And Classification

EPSS: 0.002000000 probability, percentile 0.101980000 (date 2026-08-19)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 a8e9e9450df44e9dd529ec5beff283f48f4f4b97 git Not specified
CNA Linux Linux affected bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 a261dc49d99681c9c71f38d16e31812dc3e30412 git Not specified
CNA Linux Linux affected bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 40c09b7a1d4e0a4866042c87c2bd911bb57566c8 git Not specified
CNA Linux Linux affected bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 0f19d54e2524f0bf183b82f365ae4e49b4a2f788 git Not specified
CNA Linux Linux affected bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 2dd0298905e97795a9c5ec30cf5b41975f821632 git Not specified
CNA Linux Linux affected bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 1cd4e9b7967dab48c9f79a00b06ffff7208c0993 git Not specified
CNA Linux Linux affected bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 5ccc99d58f94fad258c9c375715b3974e48620e8 git Not specified
CNA Linux Linux affected bc2bf338d54b7aadaed49bb45b9e10d4592b2a46 bbf5f639918dc011aaf60aab8480218758ee68c5 git Not specified
CNA Linux Linux affected 5.8 Not specified
CNA Linux Linux unaffected 5.8 semver Not specified
CNA Linux Linux unaffected 5.10.265 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.216 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.183 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.148 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.101 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.42 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.6 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/a8e9e9450df44e9dd529ec5beff283f48f4f4b97 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a261dc49d99681c9c71f38d16e31812dc3e30412 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2dd0298905e97795a9c5ec30cf5b41975f821632 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5ccc99d58f94fad258c9c375715b3974e48620e8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/0f19d54e2524f0bf183b82f365ae4e49b4a2f788 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/40c09b7a1d4e0a4866042c87c2bd911bb57566c8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/1cd4e9b7967dab48c9f79a00b06ffff7208c0993 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/bbf5f639918dc011aaf60aab8480218758ee68c5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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