In the Linux kernel, the following vulnerability has been resolved: entry: Fix seccomp bypass after ptrace with TSYNC Sashiko review pointed out the… (CVE-2026-89603)
A race condition vulnerability in the Linux kernel's seccomp implementation was fixed. The flaw allowed a seccomp filter installed with the TSYNC flag during a ptrace syscall stop to be bypassed because the syscall trace logic used a cached flag state. This could let an unprivileged process execute system calls that the filter was meant to block. The fix ensures the syscall work flags are re-read after ptrace handling to detect any new seccomp flags set during the ptrace stop.
AI Analysis
Technical Summary
The Linux kernel had a vulnerability where, if a thread was stopped in syscall_trace_enter() due to ptrace, another thread could install a seccomp filter with SECCOMP_FILTER_FLAG_TSYNC. The syscall_trace_enter() function used a cached 'work' variable and missed the newly set SYSCALL_WORK_SECCOMP flag, causing the seccomp filter to be bypassed. This race condition allowed unprivileged processes to execute system calls that should have been blocked by the newly installed filter. The issue was fixed by re-reading the syscall_work flags after ptrace handling to ensure any new SYSCALL_WORK_SECCOMP flags set during the ptrace stop are recognized before the seccomp check.
Potential Impact
An unprivileged process could bypass seccomp filters installed with the TSYNC flag during ptrace stops, potentially allowing execution of prohibited system calls such as execve. This undermines the security guarantees provided by seccomp filters in affected Linux kernel versions.
Mitigation Recommendations
A fix has been applied to the Linux kernel to address this race condition by re-reading syscall work flags after ptrace handling. Users should update to the fixed kernel version once available. Patch status is not explicitly confirmed in the provided data; check the vendor advisory for current remediation guidance.
In the Linux kernel, the following vulnerability has been resolved: entry: Fix seccomp bypass after ptrace with TSYNC Sashiko review pointed out the… (CVE-2026-89603)
Description
A race condition vulnerability in the Linux kernel's seccomp implementation was fixed. The flaw allowed a seccomp filter installed with the TSYNC flag during a ptrace syscall stop to be bypassed because the syscall trace logic used a cached flag state. This could let an unprivileged process execute system calls that the filter was meant to block. The fix ensures the syscall work flags are re-read after ptrace handling to detect any new seccomp flags set during the ptrace stop.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel had a vulnerability where, if a thread was stopped in syscall_trace_enter() due to ptrace, another thread could install a seccomp filter with SECCOMP_FILTER_FLAG_TSYNC. The syscall_trace_enter() function used a cached 'work' variable and missed the newly set SYSCALL_WORK_SECCOMP flag, causing the seccomp filter to be bypassed. This race condition allowed unprivileged processes to execute system calls that should have been blocked by the newly installed filter. The issue was fixed by re-reading the syscall_work flags after ptrace handling to ensure any new SYSCALL_WORK_SECCOMP flags set during the ptrace stop are recognized before the seccomp check.
Potential Impact
An unprivileged process could bypass seccomp filters installed with the TSYNC flag during ptrace stops, potentially allowing execution of prohibited system calls such as execve. This undermines the security guarantees provided by seccomp filters in affected Linux kernel versions.
Mitigation Recommendations
A fix has been applied to the Linux kernel to address this race condition by re-reading syscall work flags after ptrace handling. Users should update to the fixed kernel version once available. Patch status is not explicitly confirmed in the provided data; check the vendor advisory for current remediation guidance.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-qx6x-jhp8-p5pv
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-89603"]
Threat ID: 6aa4a00b55bf5e2cf5a86674
Added to database: 09/12/2026, 00:42:51 UTC
Last enriched: 09/12/2026, 01:02:41 UTC
Last updated: 09/12/2026, 01:02:41 UTC
Views: 2
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