CVE-2026-45957 | rcu: Fix rcu_read_unlock() deadloop due to softirq

In the Linux kernel, the following vulnerability has been resolved: rcu: Fix rcu_read_unlock() deadloop due to softirq Commit 5f5fa7ea89dc ("rcu: Don't use negative nesting depth in __rcu_read_unlock()") removes the recursion-protection code from __rcu_read_unlock(). Therefore, we could invoke the deadloop in raise_softirq_irqoff() with ftrace enabled as follows: WARNING: CPU: 0 PID: 0 at kernel/trace/trace.c:3021 __ftrace_trace_stack.constprop.0+0x172/0x180 Modules linked in: my_irq_work(O) CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G O 6.18.0-rc7-dirty #23 PREEMPT(full) Tainted: [O]=OOT_MODULE Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 RIP: 0010:__ftrace_trace_stack.constprop.0+0x172/0x180 RSP: 0018:ffffc900000034a8 EFLAGS: 00010002 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000000000 RDX: 0000000000000003 RSI: ffffffff826d7b87 RDI: ffffffff826e9329 RBP: 0000000000090009 R08: 0000000000000005 R09: ffffffff82afbc4c R10: 0000000000000008 R11: 0000000000011d7a R12: 0000000000000000 R13: ffff888003874100 R14: 0000000000000003 R15: ffff8880038c1054 FS: 0000000000000000(0000) GS:ffff8880fa8ea000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055b31fa7f540 CR3: 00000000078f4005 CR4: 0000000000770ef0 PKRU: 55555554 Call Trace: <IRQ> trace_buffer_unlock_commit_regs+0x6d/0x220 trace_event_buffer_commit+0x5c/0x260 trace_event_raw_event_softirq+0x47/0x80 raise_softirq_irqoff+0x6e/0xa0 rcu_read_unlock_special+0xb1/0x160 unwind_next_frame+0x203/0x9b0 __unwind_start+0x15d/0x1c0 arch_stack_walk+0x62/0xf0 stack_trace_save+0x48/0x70 __ftrace_trace_stack.constprop.0+0x144/0x180 trace_buffer_unlock_commit_regs+0x6d/0x220 trace_event_buffer_commit+0x5c/0x260 trace_event_raw_event_softirq+0x47/0x80 raise_softirq_irqoff+0x6e/0xa0 rcu_read_unlock_special+0xb1/0x160 unwind_next_frame+0x203/0x9b0 __unwind_start+0x15d/0x1c0 arch_stack_walk+0x62/0xf0 stack_trace_save+0x48/0x70 __ftrace_trace_stack.constprop.0+0x144/0x180 trace_buffer_unlock_commit_regs+0x6d/0x220 trace_event_buffer_commit+0x5c/0x260 trace_event_raw_event_softirq+0x47/0x80 raise_softirq_irqoff+0x6e/0xa0 rcu_read_unlock_special+0xb1/0x160 unwind_next_frame+0x203/0x9b0 __unwind_start+0x15d/0x1c0 arch_stack_walk+0x62/0xf0 stack_trace_save+0x48/0x70 __ftrace_trace_stack.constprop.0+0x144/0x180 trace_buffer_unlock_commit_regs+0x6d/0x220 trace_event_buffer_commit+0x5c/0x260 trace_event_raw_event_softirq+0x47/0x80 raise_softirq_irqoff+0x6e/0xa0 rcu_read_unlock_special+0xb1/0x160 __is_insn_slot_addr+0x54/0x70 kernel_text_address+0x48/0xc0 __kernel_text_address+0xd/0x40 unwind_get_return_address+0x1e/0x40 arch_stack_walk+0x9c/0xf0 stack_trace_save+0x48/0x70 __ftrace_trace_stack.constprop.0+0x144/0x180 trace_buffer_unlock_commit_regs+0x6d/0x220 trace_event_buffer_commit+0x5c/0x260 trace_event_raw_event_softirq+0x47/0x80 __raise_softirq_irqoff+0x61/0x80 __flush_smp_call_function_queue+0x115/0x420 __sysvec_call_function_single+0x17/0xb0 sysvec_call_function_single+0x8c/0xc0 </IRQ> Commit b41642c87716 ("rcu: Fix rcu_read_unlock() deadloop due to IRQ work") fixed the infinite loop in rcu_read_unlock_special() for IRQ work by setting a flag before calling irq_work_queue_on(). We fix this issue by setting the same flag before calling raise_softirq_irqoff() and rename the flag to defer_qs_pending for more common.

Published: 2026-05-27 Last update: 2026-05-27 Assigner: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD Status：Awaiting Analysis，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-45957 is rated Low Risk (5.2/100): low exploitation likelihood (EPSS 0.02%). 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-2026-45957

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 2026-05-28 — 0.02% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-45957

CVSS metrics for this CVE.

No CVSS data in dataset for this CVE.

Weakness enumeration for CVE-2026-45957

GitHub Security Advisory for CVE-2026-45957

GHSA-hmgm-22hx-5rp9 · Severity: unknown — In the Linux kernel, the following vulnerability has been resolved: rcu: Fix rcu_read_unlock()...

OS Trackers for CVE-2026-45957

vendor priority summary link
debian not yet assigned CVE-2026-45957 not yet assigned 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-2026-45957
redhat medium — https://access.redhat.com/security/cve/CVE-2026-45957
suse — — https://www.suse.com/security/cve/CVE-2026-45957/
ubuntu medium CVE-2026-45957 medium priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 891 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): DNE 508, needs-triage 224, ignored 159. https://ubuntu.com/security/CVE-2026-45957

Affected software / configurations for CVE-2026-45957

Vendor Product Version Raw CPE
No affected products in dataset.

References for CVE-2026-45957

cvelogic Threat Intelligence