Kernel-level bug in the Linux kernel can bypass seccomp and enable sandbox/container escape and privilege escalation on widely deployed systems; broad operational impact.
CVE-2026-89603
Local Linux kernel seccomp bypass via ptrace TSYNC race
Is CVE-2026-89603 being exploited?
Not confirmed. CVE-2026-89603 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.14% probability of exploitation in the next 30 days.
How severe is CVE-2026-89603?
CVE-2026-89603 is rated High with a CVSS score of 8.4. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-89603?
Yes. A fix has been recorded for CVE-2026-89603. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-89603 affect?
CVE-2026-89603 affects Linux kernel (stable releases), Containers using seccomp profiles, Applications relying on ptrace-based tracing. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-89603?
Install vendor kernel patches or livepatch, restrict ptrace access, and reboot if required.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Local unprivileged process can bypass seccomp filters via ptrace TSYNC race to execute blocked syscalls, enabling sandbox escape and potential privilege escalation.
Immediate action required
- affected>= 142781e108b13b2b0e8f035cfb5bfbbc8f14d887 and < 459f33f82864723a7fa366cf1091d9c6c893b6b2
- affected>= 142781e108b13b2b0e8f035cfb5bfbbc8f14d887 and < ab4647459098a43e9d6fdb860836f08c962f3774
- affected>= 142781e108b13b2b0e8f035cfb5bfbbc8f14d887 and < 4a3591287fb7f808e209b4974ed337f609a2006b
- affected5.9
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.