{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89603","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-11T19:38:34.732Z","datePublished":"2026-09-11T19:45:06.613Z","dateUpdated":"2026-09-14T12:01:23.522Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-14T12:01:23.522Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nentry: Fix seccomp bypass after ptrace with TSYNC\n\nSashiko review pointed out the following issue.\n\nIf a thread is stopped in syscall_trace_enter() for ptrace, another\nthread can install a seccomp filter with SECCOMP_FILTER_FLAG_TSYNC\n(e.g., via seccomp_attach_filter()). This will successfully set\nSYSCALL_WORK_SECCOMP on the stopped thread, but syscall_trace_enter()\nevaluates a cached 'work' variable sampled on entry. Consequently,\nthe subsequent check for SYSCALL_WORK_SECCOMP misses the newly\nassigned flag, and the filter is silently bypassed.\n\nThis race condition could allow an unprivileged process to execute\na prohibited system call (e.g., execve) that the newly installed filter\nwas intended to block, especially since the tracer might have modified\nthe system call number during the ptrace stop.\n\nFix this by re-reading the syscall_work flags after ptrace handling,\nso that any new SYSCALL_WORK_SECCOMP flag set by another thread via\nTSYNC during the ptrace stop is observed before the subsequent\nseccomp check."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N","baseScore":8.4,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The bypass is reached only through local syscalls: syscall_enter_from_user_mode_work() -> syscall_trace_enter() while the thread is stopped for ptrace(PTRACE_SYSCALL/PTRACE_SYSEMU), plus seccomp(SECCOMP_SET_MODE_FILTER, SECCOMP_FILTER_FLAG_TSYNC) from a sibling thread. There is no network, adjacent, or physical path.\nAC:L - The ptrace syscall-enter stop blocks indefinitely, so the attacker controls both sides: a helper thread can TSYNC the filter during that stop, then the tracer resumes. This is an attacker-driven window rather than a tight race, and a deterministic reproducer exists.\nPR:L - An ordinary local user can PTRACE_TRACEME/PTRACE_SYSCALL their own child (allowed under default Yama ptrace_scope=1) and install a filter after prctl(PR_SET_NO_NEW_PRIVS) or with CAP_SYS_ADMIN in a user namespace. Init-namespace root is not required.\nUI:N - The attacker drives ptrace, TSYNC, and the in-flight syscall themselves. No separate victim action such as opening a file or mounting a filesystem is required.\nS:C - Seccomp is a confinement sandbox installed by a parent or sandboxing thread. Skipping the newly TSYNC'd filter lets a thread execute a syscall that authority intended to block, which is a sandbox escape across that security boundary.\nC:H - The skipped check allows an arbitrary blocked syscall to run, including read-oriented calls the filter was meant to deny (process_vm_readv, ptrace PEEK, bpf, or argument-filtered open/read), disclosing data outside the sandbox policy.\nI:H - Seccomp is supposed to run after ptrace so a tracer cannot rewrite the syscall number past the filter; this stale-flag skip lets that rewritten call be execve, process_vm_writev, ptrace, mount, or another integrity-affecting syscall the new filter was installed to prevent.\nA:N - This is a stale syscall_work flag causing a seccomp policy bypass, not memory corruption. It does not oops, panic, deadlock, or hang the kernel."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/entry-common.h"],"versions":[{"version":"142781e108b13b2b0e8f035cfb5bfbbc8f14d887","lessThan":"eca5ed4200f0be3e91f8a237b1f37582030a93a8","status":"affected","versionType":"git"},{"version":"142781e108b13b2b0e8f035cfb5bfbbc8f14d887","lessThan":"8709e7e1dd7d7de0651e61700edf24f5784f9243","status":"affected","versionType":"git"},{"version":"142781e108b13b2b0e8f035cfb5bfbbc8f14d887","lessThan":"22bb836fc133331982c264227a899d4b26a09706","status":"affected","versionType":"git"},{"version":"142781e108b13b2b0e8f035cfb5bfbbc8f14d887","lessThan":"23001ee5d8631e30192cde6f6d3ccb6805570499","status":"affected","versionType":"git"},{"version":"142781e108b13b2b0e8f035cfb5bfbbc8f14d887","lessThan":"09e8880ce5409bdb84da991b053d7087502c181e","status":"affected","versionType":"git"},{"version":"142781e108b13b2b0e8f035cfb5bfbbc8f14d887","lessThan":"459f33f82864723a7fa366cf1091d9c6c893b6b2","status":"affected","versionType":"git"},{"version":"142781e108b13b2b0e8f035cfb5bfbbc8f14d887","lessThan":"ab4647459098a43e9d6fdb860836f08c962f3774","status":"affected","versionType":"git"},{"version":"142781e108b13b2b0e8f035cfb5bfbbc8f14d887","lessThan":"4a3591287fb7f808e209b4974ed337f609a2006b","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/entry-common.h"],"versions":[{"version":"5.9","status":"affected"},{"version":"0","lessThan":"5.9","status":"unaffected","versionType":"semver"},{"version":"5.10.270","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.221","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.188","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.157","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.110","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.51","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.4","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3-rc1","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.9","versionEndExcluding":"5.10.270"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.9","versionEndExcluding":"5.15.221"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.9","versionEndExcluding":"6.1.188"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.9","versionEndExcluding":"6.6.157"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.9","versionEndExcluding":"6.12.110"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.9","versionEndExcluding":"6.18.51"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.9","versionEndExcluding":"7.2.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.9","versionEndExcluding":"7.3-rc1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/eca5ed4200f0be3e91f8a237b1f37582030a93a8"},{"url":"https://git.kernel.org/stable/c/8709e7e1dd7d7de0651e61700edf24f5784f9243"},{"url":"https://git.kernel.org/stable/c/22bb836fc133331982c264227a899d4b26a09706"},{"url":"https://git.kernel.org/stable/c/23001ee5d8631e30192cde6f6d3ccb6805570499"},{"url":"https://git.kernel.org/stable/c/09e8880ce5409bdb84da991b053d7087502c181e"},{"url":"https://git.kernel.org/stable/c/459f33f82864723a7fa366cf1091d9c6c893b6b2"},{"url":"https://git.kernel.org/stable/c/ab4647459098a43e9d6fdb860836f08c962f3774"},{"url":"https://git.kernel.org/stable/c/4a3591287fb7f808e209b4974ed337f609a2006b"}],"title":"entry: Fix seccomp bypass after ptrace with TSYNC","x_generator":{"engine":"bippy-1.2.0"}}}}