{"id":"CVE-2026-80778","title":"futex/pi: Reject cross-mm private futex owners","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nfutex/pi: Reject cross-mm private futex owners\n\nA private futex key borrows the waiter's mm without taking an mm_users\nreference. Nevertheless, attach_to_pi_owner() cur…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 80367ad01d93ac781b0e1df246edaf006928002f < 2b92e5562653b5293529f63b0300837d9dcedbd7","Linux >= 80367ad01d93ac781b0e1df246edaf006928002f < f7fb3e07752688842cbe0b85cf0d98c2fbf76b68","Linux >= 80367ad01d93ac781b0e1df246edaf006928002f < 43b148d796aa338858792d0167cebdc12b8cb4b9","Linux >= 80367ad01d93ac781b0e1df246edaf006928002f < 59b3732f95dda1fbd2234514d35f4fb6b5bb6d85","Linux 6.16"],"published":"2026-09-04","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:43:33.681Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-80778","references":[{"url":"https://git.kernel.org/stable/c/2b92e5562653b5293529f63b0300837d9dcedbd7"},{"url":"https://git.kernel.org/stable/c/f7fb3e07752688842cbe0b85cf0d98c2fbf76b68"},{"url":"https://git.kernel.org/stable/c/43b148d796aa338858792d0167cebdc12b8cb4b9"},{"url":"https://git.kernel.org/stable/c/59b3732f95dda1fbd2234514d35f4fb6b5bb6d85"}],"tags":["cve.org"],"epss":0.00168,"epssPercentile":0.05671,"ingestedAt":"2026-10-19T10:20:54.955Z","slug":"CVE-2026-80778","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nfutex/pi: Reject cross-mm private futex owners\n\nA private futex key borrows the waiter's mm without taking an mm_users\nreference. Nevertheless, attach_to_pi_owner() currently accepts an owner\nfrom a different address space and copies the private key into the owner's\nPI state.\n\nWhen that owner exits, exit_pi_state_list() uses the saved key to find the\nhash bucket and acquires a reference to the waiter's private hash. If the\nlast user of the waiter's mm exits concurrently, futex_hash_free() frees\nthe hash while the owner still uses its bucket and reference.\n\nPrevent this by validating in attach_to_pi_owner() that, for private\nfutexes, the owner mm and waiter mm are the same. Perform the check with\nthe owner's pi_lock held and after validating owner::futex::state to\nserialize against a concurrent PI-state exit cleanup.\n\n[ tglx: Amended comment ]\n\n## Affected\n\n- `Linux >= 80367ad01d93ac781b0e1df246edaf006928002f < 2b92e5562653b5293529f63b0300837d9dcedbd7`\n- `Linux >= 80367ad01d93ac781b0e1df246edaf006928002f < f7fb3e07752688842cbe0b85cf0d98c2fbf76b68`\n- `Linux >= 80367ad01d93ac781b0e1df246edaf006928002f < 43b148d796aa338858792d0167cebdc12b8cb4b9`\n- `Linux >= 80367ad01d93ac781b0e1df246edaf006928002f < 59b3732f95dda1fbd2234514d35f4fb6b5bb6d85`\n- `Linux 6.16`\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":[]}