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CVE-2025-39744· NVD / CVE Program· CNA Linux

rcu: Fix rcu_read_unlock() deadloop due to IRQ work

In the Linux kernel, the following vulnerability has been resolved: rcu: Fix rcu_read_unlock() deadloop due to IRQ work During rcu_read_unlock_special(), if this happens during irq_exit(), we can lockup if an IPI is issued. This is because the IPI itself triggers the irq_exit() path causing a recursive lock up. This is precisely what Xiongfeng found when invoking a BPF program on the trace_tick_stop() tracepoint As shown in the trace below. Fix by managing the irq_work state correctly. irq_exit() __irq_exit_rcu() /* in_hardirq() returns false after this */ preempt_count_sub(HARDIRQ_OFFSET) tick_irq_exit() tick_nohz_irq_exit() tick_nohz_stop_sched_tick() trace_tick_stop() /* a bpf prog is hooked on this trace point */ __bpf_trace_tick_stop() bpf_trace_run2() rcu_read_unlock_special() /* will send a IPI to itself */ irq_work_queue_on(&rdp->defer_qs_iw, rdp->cpu); A simple reproducer can also be obtained by doing the following in tick_irq_exit(). It will hang on boot without the patch: static inline void tick_irq_exit(void) { + rcu_read_lock(); + WRITE_ONCE(current->rcu_read_unlock_special.b.need_qs, true); + rcu_read_unlock(); + [neeraj: Apply Frederic's suggested fix for PREEMPT_RT]

HighCVSS 7.1 · v3.1—No exploit Fix available
Published
Sep 11, 2025
Updated
Jun 17, 2026
EPSS
0.2% · 4th percentile
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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 · 0.2%

Affected systems

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 kernelbefore 6.6.103
  • linux linux kernel6.7 and later · before 6.12.43
  • linux linux kernel6.13 and later · before 6.15.11
  • linux linux kernel6.16 and later · before 6.16.2

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

    • 5.3affected
    • 0864f057b050bc6dd68106b3185e02db5140012d and later · before e7a375453cca2b8a0d2fa1b82b913f3fed7c0507affected · git
    • 0864f057b050bc6dd68106b3185e02db5140012d and later · before 1cfa244f7198d325594e627574930b7b91df5bfeaffected · git
    • 0864f057b050bc6dd68106b3185e02db5140012d and later · before ddebb2a7677673cf4438a04e1a48b8ed6b0c8e9aaffected · git
    • 0864f057b050bc6dd68106b3185e02db5140012d and later · before 56c5ef194f4509df63fc0f7a91ea5973ce479b1eaffected · git
    • 0864f057b050bc6dd68106b3185e02db5140012d and later · before b41642c87716bbd09797b1e4ea7d904f06c39b7baffected · git
    • before 5.3not affected · semver
    • 6.6.103 and later · up to and including 6.6.*not affected · semver
    • 6.12.43 and later · up to and including 6.12.*not affected · semver
    • 6.15.11 and later · up to and including 6.15.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxall versions—
Debian:13linuxbefore 6.12.43-16.12.43-1
Debian:14linuxbefore 6.16.3-16.16.3-1

Same product

linux: all records

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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 Linux1cfa244f7198d325594e627574930b7b91df5bfeVendor (CNA)
Linux Linux56c5ef194f4509df63fc0f7a91ea5973ce479b1eVendor (CNA)
Linux Linuxb41642c87716bbd09797b1e4ea7d904f06c39b7bVendor (CNA)
Linux Linuxddebb2a7677673cf4438a04e1a48b8ed6b0c8e9aVendor (CNA)
Linux Linuxe7a375453cca2b8a0d2fa1b82b913f3fed7c0507Vendor (CNA)
debian:linux6.12.43-1 · 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.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

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).

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

—

Noroxi analysis

No Noroxi analysis for this record yet

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Change log

  1. Fix✗ → ✓

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References

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

All records