CVE-2026-53163 | locking/rtmutex: Skip remove_waiter() when waiter is not enqueued

In the Linux kernel, the following vulnerability has been resolved: locking/rtmutex: Skip remove_waiter() when waiter is not enqueued syzbot triggered the following splat in remove_waiter() via FUTEX_CMP_REQUEUE_PI: KASAN: null-ptr-deref in range [0x0000000000000a88-0x0000000000000a8f] class_raw_spinlock_constructor remove_waiter+0x159/0x1200 kernel/locking/rtmutex.c:1561 rt_mutex_start_proxy_lock+0x103/0x120 futex_requeue+0x10e4/0x20d0 __x64_sys_futex+0x34f/0x4d0 task_blocks_on_rt_mutex() does not arm the waiter upon deadlock detection, leaving waiter->task nil, where 3bfdc63936dd ("rtmutex: Use waiter::task instead of current in remove_waiter()") made this fatal. Furthermore, rt_mutex_start_proxy_lock() should not be calling into remove_waiter() upon a successfully grabbing the rtmutex. 1a1fb985f2e2 ("futex: Handle early deadlock return correctly"), moved the remove_waiter() out of __rt_mutex_start_proxy_lock() (where 'ret' was only ever 0 or < 0) into the wrapper. Tighten this check to account for try_to_take_rt_mutex().

Published: 2026-06-25 Last update: 2026-06-30 Assigner: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Conclusion & alert: CVE-2026-53163 is rated Low Risk (7/100): low exploitation likelihood (EPSS 0.17%). Mandatory action: Low composite risk—no urgent action required; patch on your normal maintenance cycle and revisit priority if CVSS or EPSS increases.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-53163

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-25 0.17%

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-53163

CVSS metrics for this CVE.

No CVSS data in dataset for this CVE.

Weakness enumeration for CVE-2026-53163

GitHub Security Advisory for CVE-2026-53163

GHSA-4w7w-2mrj-36vw · Severity: unknown — In the Linux kernel, the following vulnerability has been resolved: locking/rtmutex: Skip...

OS Trackers for CVE-2026-53163

vendor priority summary link
debian unimportant CVE-2026-53163 unimportant priority: Debian including 1 source packages (linux), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 3, open 2. https://security-tracker.debian.org/tracker/CVE-2026-53163
redhat medium https://access.redhat.com/security/cve/CVE-2026-53163
suse medium CVE-2026-53163 severity moderate: SUSE including 8 source package names (kernel-default, kernel-default-base, …), 30 product×package rows across 7 product lines (SUSE Linux Enterprise Micro 5.0, SUSE Linux Enterprise Micro 5.1, … (7 product lines)): Known Not Affected 30. https://www.suse.com/security/cve/CVE-2026-53163/
ubuntu medium CVE-2026-53163 medium priority: Ubuntu including 161 source packages (linux, linux-allwinner-5.19, …), 1449 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): DNE 1044, ignored 172, not-affected 130, released 87, needed 15, needs-triage 1. https://ubuntu.com/security/CVE-2026-53163

Affected software / configurations for CVE-2026-53163

Vendor Product Version Raw CPE
linux linux_kernel >= 6.18.27, < 6.18.36 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 7.0.4, < 7.0.13 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.1.175 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.6.140 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.12.86 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

References for CVE-2026-53163

cvelogic Threat Intelligence