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Review reviewCritical

CVE-2026-53260

Linux Linux, linux kernel

In the Linux kernel, the following vulnerability has been resolved: tcp: Add preempt_{disable,enable}_nested() in reqsk_queue_hash_req(). syzbot reported a weird reqsk->rsk_refcnt underflow in __inet_csk_reqsk_queue_drop(). The captured reqsk_put() in __inet_csk_reqsk_queue_drop() is called only when it successfully removes reqsk from ehash. Moreover, reqsk_timer_handler() calls another reqsk_put() after that. This indicates that the reqsk was missing both refcnts for ehash and the timer itself. Since all the syzbot reports had PREEMPT_RT enabled, the only possible scenario is that reqsk_qu...

CVSS
9.8
EPSS
0.37%
29.5% percentile
CISA KEV
Not listed
Published
2026.06.25
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability0.37%
Technical severityCVSS 9.8

Vulnerability overview

In the Linux kernel, the following vulnerability has been resolved: tcp: Add preempt_{disable,enable}_nested() in reqsk_queue_hash_req(). syzbot reported a weird reqsk->rsk_refcnt underflow in __inet_csk_reqsk_queue_drop(). The captured reqsk_put() in __inet_csk_reqsk_queue_drop() is called only when it successfully removes reqsk from ehash. Moreover, reqsk_timer_handler() calls another reqsk_put() after that. This indicates that the reqsk was missing both refcnts for ehash and the timer itself. Since all the syzbot reports had PREEMPT_RT enabled, the only possible scenario is that reqsk_qu...

Affected product and versions

Product
Linux Linux, linux kernel
Affected versions
>= d2d6422f8bd17c6bb205133e290625a564194496 < 889fc99967007e2493833515a645cb2d800f6742, >= d2d6422f8bd17c6bb205133e290625a564194496 < de5a46f3b2c8d3cd20afa158bd3a725e3e3d6fd3, >= d2d6422f8bd17c6bb205133e290625a564194496 < b183215ff714efb747d9d5a429322ba6404b5401, >= d2d6422f8bd17c6bb205133e290625a564194496 < e10902df24488ca722303133acfc82490f7d59ad, >= 6.12, >= 6.12 < 7.0.13, 7.1
Fixed versions
7.0.13

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux Linux, linux kernel and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE
CWE-416
CVE-2026-53260 — Linux Linux, linux kernel | SECUFOCUS NOW