{"id":"CVE-2026-43178","state":"PUBLISHED","title":"procfs: fix possible double mmput() in do_procmap_query()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nprocfs: fix possible double mmput() in do_procmap_query()\n\nWhen user provides incorrectly sized buffer for build ID for PROCMAP_QUERY\nwe return with -ENAMETOOLONG error.  After recent changes this condition\nhappens later, after we unlocked mmap_lock/per-VMA lock and did mmput(),\nso original goto out is now wrong and will double-mmput() mm_struct.  Fix\nby jumping further to clean up only vm_file and name_buf.","publishedAt":"2026-05-06T11:27:51.524Z","updatedAt":"2026-08-05T12:26:20.039Z","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":"b9b97e6aeb534315f9646b2090d1a5024c6a4e82","status":"affected","lessThan":"f9fe092084cd04deea18747f58a2304026e76aaa","versionType":"git"},{"version":"cbc03ce3e6ce7e21214c3f02218213574c1a2d08","status":"affected","lessThan":"8adaff87db143583e08eec4f4e7788f1ef8af94d","versionType":"git"},{"version":"b5cbacd7f86f4f62b8813688c8e73be94e8e1951","status":"affected","lessThan":"90f5e87c9b75833b9ef3a4415b92c0247f28ab2f","versionType":"git"},{"version":"b5cbacd7f86f4f62b8813688c8e73be94e8e1951","status":"affected","lessThan":"61dc9f776705d6db6847c101b98fa4f0e9eb6fa3","versionType":"git"},{"version":"6.12.70","status":"affected","lessThan":"6.12.75","versionType":"semver"},{"version":"6.18.10","status":"affected","lessThan":"6.18.16","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/proc/task_mmu.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.19","versionType":"semver"},{"version":"6.12.75","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.16","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.6","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/proc/task_mmu.c"]}],"references":["https://git.kernel.org/stable/c/f9fe092084cd04deea18747f58a2304026e76aaa","https://git.kernel.org/stable/c/8adaff87db143583e08eec4f4e7788f1ef8af94d","https://git.kernel.org/stable/c/90f5e87c9b75833b9ef3a4415b92c0247f28ab2f","https://git.kernel.org/stable/c/61dc9f776705d6db6847c101b98fa4f0e9eb6fa3","https://access.redhat.com/security/cve/CVE-2026-43178","https://bugzilla.redhat.com/show_bug.cgi?id=2467227","https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43178.json"],"weaknesses":["CWE-1341"],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/43xxx/CVE-2026-43178.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-43178","state":"PUBLISHED","datePublished":"2026-05-06T11:27:51.524Z","dateUpdated":"2026-08-05T12:26:20.039Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-01T14:12:55.991Z"},"containers":{"cna":{"title":"procfs: fix possible double mmput() in do_procmap_query()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nprocfs: fix possible double mmput() in do_procmap_query()\n\nWhen user provides incorrectly sized buffer for build ID for PROCMAP_QUERY\nwe return with -ENAMETOOLONG error.  After recent changes this condition\nhappens later, after we unlocked mmap_lock/per-VMA lock and did mmput(),\nso original goto out is now wrong and will double-mmput() mm_struct.  Fix\nby jumping further to clean up only vm_file and name_buf."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"b9b97e6aeb534315f9646b2090d1a5024c6a4e82","status":"affected","lessThan":"f9fe092084cd04deea18747f58a2304026e76aaa","versionType":"git"},{"version":"cbc03ce3e6ce7e21214c3f02218213574c1a2d08","status":"affected","lessThan":"8adaff87db143583e08eec4f4e7788f1ef8af94d","versionType":"git"},{"version":"b5cbacd7f86f4f62b8813688c8e73be94e8e1951","status":"affected","lessThan":"90f5e87c9b75833b9ef3a4415b92c0247f28ab2f","versionType":"git"},{"version":"b5cbacd7f86f4f62b8813688c8e73be94e8e1951","status":"affected","lessThan":"61dc9f776705d6db6847c101b98fa4f0e9eb6fa3","versionType":"git"},{"version":"6.12.70","status":"affected","lessThan":"6.12.75","versionType":"semver"},{"version":"6.18.10","status":"affected","lessThan":"6.18.16","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/proc/task_mmu.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.19","versionType":"semver"},{"version":"6.12.75","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.16","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.6","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/proc/task_mmu.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/f9fe092084cd04deea18747f58a2304026e76aaa"},{"url":"https://git.kernel.org/stable/c/8adaff87db143583e08eec4f4e7788f1ef8af94d"},{"url":"https://git.kernel.org/stable/c/90f5e87c9b75833b9ef3a4415b92c0247f28ab2f"},{"url":"https://git.kernel.org/stable/c/61dc9f776705d6db6847c101b98fa4f0e9eb6fa3"}],"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 vulnerable path is reached through a local `ioctl(PROCMAP_QUERY)` on `/proc/<pid>/maps`; there is no network, adjacent, or physical attack path.\nAC:L - The trigger is deterministic: choose a file-backed VMA with a build ID and pass a nonzero build ID buffer smaller than the parsed build ID. No attacker-uncontrolled race or rare state is required.\nPR:L - An unprivileged local user can open and query `/proc/self/maps`; ptrace-style checks only restrict querying other processes. No real root or namespace-derived administrative capability is needed for self-triggering.\nUI:N - The attacker can perform the mapping and ioctl directly in their own process. No victim user action is required.\nS:U - The vulnerability corrupts kernel memory-management state within the same OS security authority. It is not a VM escape, IOMMU bypass, or cross-authority boundary violation.\nC:H - The double `mmput()` can prematurely run `__mmput()`/`exit_mmap()` and later free an mm still in use, creating use-after-free/refcount corruption of memory-management structures. Under the higher-severity rule, this is treated as capable of enabling high-impact information disclosure.\nI:H - Premature teardown/freeing of a live mm and page-table related state is memory-management corruption with plausible use-after-free exploitation potential. Under the higher-severity rule, this supports high integrity impact.\nA:H - Syzbot observed a kernel `__mmdrop()` warning with `mm == current->mm`, and the bug can tear down or free a live address space. 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