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NVD / CVE Program· CNA Linux

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

Noroxi assessment

Priority: Monitor (action score 28/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.12% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 1f16679a5aa60238466ce339c35f5e82ece60337, 4a4a6e12c9c829be3f74b7206fa8640fc4e1c566, 979c708e6c9d7fc461daef2dad8b45f22e23464c.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 1f16679a5aa60238466ce339c35f5e82ece60337, 4a4a6e12c9c829be3f74b7206fa8640fc4e1c566, 979c708e6c9d7fc461daef2dad8b45f22e23464c or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 7.1 · v3.1—No exploit Fix available
Published
May 27, 2026
Updated
Oct 30, 2026
EPSS
0.1% · 2th percentile

Report tools

JSON

Action score

28

Monitor

Low priority for now.

CVSS
28 / 40 · 7.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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When you'll hear from us

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  • when exploit code appears or is weaponized
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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel5.8 and later · before 6.6.128
  • linux linux kernel6.7 and later · before 6.12.75
  • linux linux kernel6.13 and later · before 6.18.14
  • linux linux kernel6.19 and later · before 6.19.4

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 5.8affected
    • 5f5fa7ea89dc82d34ed458f4d7a8634e8e9eefce and later · before d36d8a7cf0e1d52ccde290855782b7b2ffc78f63affected · git
    • 5f5fa7ea89dc82d34ed458f4d7a8634e8e9eefce and later · before 979c708e6c9d7fc461daef2dad8b45f22e23464caffected · git
    • 5f5fa7ea89dc82d34ed458f4d7a8634e8e9eefce and later · before 1f16679a5aa60238466ce339c35f5e82ece60337affected · git
    • 5f5fa7ea89dc82d34ed458f4d7a8634e8e9eefce and later · before 4a4a6e12c9c829be3f74b7206fa8640fc4e1c566affected · git
    • 5f5fa7ea89dc82d34ed458f4d7a8634e8e9eefce and later · before c2932e16d8c354404b17123e64daa8e33191e145affected · git
    • 5f5fa7ea89dc82d34ed458f4d7a8634e8e9eefce and later · before d41e37f26b3157b3f1d10223863519a943aa239baffected · git
    • before 5.8not affected · semver
    • 6.1.191 and later · up to and including 6.1.*not affected · semver
    • 6.6.128 and later · up to and including 6.6.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:13linuxbefore 6.12.85-16.12.85-1
Debian:14linuxbefore 6.18.14-16.18.14-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-45955May 27, 2026 · md/md-llbitmap: fix percpu_ref not resurrected on suspend timeout
    28Monitor
  • ← EarlierCVE-2026-45956May 27, 2026 · drm/exynos: vidi: use priv->vidi_dev for ctx lookup in vidi_connection_ioctl()
    31Monitor
  • Later →CVE-2026-45959May 27, 2026 · crypto: ccp - Fix a crash due to incorrect cleanup usage of kfree
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux1f16679a5aa60238466ce339c35f5e82ece60337Vendor (CNA)
Linux Linux4a4a6e12c9c829be3f74b7206fa8640fc4e1c566Vendor (CNA)
Linux Linux979c708e6c9d7fc461daef2dad8b45f22e23464cVendor (CNA)
Linux Linuxc2932e16d8c354404b17123e64daa8e33191e145Vendor (CNA)
Linux Linuxd36d8a7cf0e1d52ccde290855782b7b2ffc78f63Vendor (CNA)
Linux Linuxd41e37f26b3157b3f1d10223863519a943aa239bVendor (CNA)
debian:linux6.12.85-1 · Debian:13Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records