entry: Fix seccomp bypass after ptrace with TSYNC
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · None
- Fix status
- Partial Red Hat: 2 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.
Summary
In the Linux kernel, the following vulnerability has been resolved: entry: Fix seccomp bypass after ptrace with TSYNC Sashiko review pointed out the following issue. If a thread is stopped in syscall_trace_enter() for ptrace, another thread can install a seccomp filter with SECCOMP_FILTER_FLAG_TSYNC (e.g., via seccomp_attach_filter()). This will successfully set SYSCALL_WORK_SECCOMP on the stopped thread, but syscall_trace_enter() evaluates a cached 'work' variable sampled on entry. Consequently, the subsequent check for SYSCALL_WORK_SECCOMP misses the newly assigned flag, and the filter is silently bypassed. This race condition could allow an unprivileged process to execute a prohibited system call (e.g., execve) that the newly installed filter was intended to block, especially since the tracer might have modified the system call number during the ptrace stop. Fix this by re-reading the syscall_work flags after ptrace handling, so that any new SYSCALL_WORK_SECCOMP flag set by another thread via TSYNC during the ptrace stop is observed before the subsequent seccomp check.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 5.9 and later | 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, 6.18.51, 7.2.4, 7.3-rc1 | Patch available | CNA |
- Linux VendorLinux Affected 5.9 and later Fixed in 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, 6.18.51, 7.2.4, 7.3-rc1 Patch available CNA
Remediation
- Fix · CNA Linux (Linux) Fixed in 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, 6.18.51, 7.2.4, 7.3-rc1
Red Hat 2 advisories
- RHSA-2026:93413 Released 2026-11-01 · Red Hat rating Importantkernel security, bug fix, and enhancement update
- 10Base-SMTV kernel-modules-internal-6.12.0-211.72.1.el10_2
- Red Hat Enterprise Linux AppStream (v. 10) kernel-64k-debug-devel-6.12.0-211.72.1.el10_2, kernel-64k-debug-devel-matched-6.12.0-211.72.1.el10_2, kernel-64k-devel-6.12.0-211.72.1.el10_2 +12
- Red Hat Enterprise Linux BaseOS (v. 10) kernel-6.12.0-211.72.1.el10_2, kernel-64k-6.12.0-211.72.1.el10_2, kernel-64k-core-6.12.0-211.72.1.el10_2 +29
- Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) kernel-tools-libs-devel-6.12.0-211.72.1.el10_2, libperf-6.12.0-211.72.1.el10_2
- Red Hat Enterprise Linux Hidden (v. 10) kernel-modules-internal-6.12.0-211.72.1.el10_2
- Red Hat Enterprise Linux Real Time (v. 10) kernel-rt-6.12.0-211.72.1.el10_2, kernel-rt-64k-6.12.0-211.72.1.el10_2, kernel-rt-64k-core-6.12.0-211.72.1.el10_2 +21
- Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt-6.12.0-211.72.1.el10_2, kernel-rt-core-6.12.0-211.72.1.el10_2, kernel-rt-debug-6.12.0-211.72.1.el10_2 +9
- RHSA-2026:93412 Released 2026-11-01 · Red Hat rating Importantkernel security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream (v. 9) kernel-64k-debug-devel-5.14.0-687.64.1.el9_8, kernel-64k-debug-devel-matched-5.14.0-687.64.1.el9_8, kernel-64k-devel-5.14.0-687.64.1.el9_8 +12
- Red Hat Enterprise Linux BaseOS (v. 9) kernel-5.14.0-687.64.1.el9_8, kernel-64k-5.14.0-687.64.1.el9_8, kernel-64k-core-5.14.0-687.64.1.el9_8 +28
- Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) kernel-tools-libs-devel-5.14.0-687.64.1.el9_8, libperf-5.14.0-687.64.1.el9_8
- Red Hat Enterprise Linux Real Time (v. 9) kernel-rt-5.14.0-687.64.1.el9_8, kernel-rt-64k-5.14.0-687.64.1.el9_8, kernel-rt-64k-core-5.14.0-687.64.1.el9_8 +21
- Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt-5.14.0-687.64.1.el9_8, kernel-rt-core-5.14.0-687.64.1.el9_8, kernel-rt-debug-5.14.0-687.64.1.el9_8 +9
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet |
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
Not affected: 3 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
Timeline
- 2026-10-02 Threatist record created from CVE-2026-89603
- 2026-10-03 Alias added: GHSA-qx6x-jhp8-p5pv
- 2026-11-02 Fix available: RHSA-2026:93413 · Red Hat
- 2026-11-02 Fix available: RHSA-2026:93412 · Red Hat
References
Other 8
- https://git.kernel.org/stable/c/eca5ed4200f0be3e91f8a237b1f37582030a93a8
- https://git.kernel.org/stable/c/8709e7e1dd7d7de0651e61700edf24f5784f9243
- https://git.kernel.org/stable/c/22bb836fc133331982c264227a899d4b26a09706
- https://git.kernel.org/stable/c/23001ee5d8631e30192cde6f6d3ccb6805570499
- https://git.kernel.org/stable/c/09e8880ce5409bdb84da991b053d7087502c181e
- https://git.kernel.org/stable/c/459f33f82864723a7fa366cf1091d9c6c893b6b2
- https://git.kernel.org/stable/c/ab4647459098a43e9d6fdb860836f08c962f3774
- https://git.kernel.org/stable/c/4a3591287fb7f808e209b4974ed337f609a2006b
More Linux vulnerabilities
- TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
- TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
- TI-2021-02452 Incorrect authorization in Ubuntu linux kernel KEVCVSS 3.1HIGH 8.8
- TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
- TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
- TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
Sources
- CVE-2026-89603 · CVE Program
- CVE-2026-89603 · NVD
- FIRST EPSS
- GHSA-qx6x-jhp8-p5pv · GitHub Advisory Database · CC BY 4.0
- CVE-2026-89603 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences