CVE-2026-53260

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-06-25. a secondary CVSS source baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.8Exploit: None knownExposed: 0

A fix is available — apply it.

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_queue_hash_req() is preempted after mod_timer() and before refcount_set(), and then the timer triggered after 1s aborts the reqsk due to its listener's close().

Let's wrap mod_timer() and refcount_set() with preempt_disable_nested() and preempt_enable_nested().

Note that inet_ehash_insert() holds the normal spin_lock() (mutex in PREEMPT_RT), so it must be called outside of preempt_disable_nested(), but this is fine.

The lookup path just ignores 0 sk_refcnt entries in ehash and tries to create another reqsk, but this will fail at inet_ehash_insert().

[0]: refcount_t: underflow; use-after-free. WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28, CPU#0: ktimers/0/16 Modules linked in: CPU: 0 UID: 0 PID: 16 Comm: ktimers/0 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 RIP: 0010:refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28 Code: e4 7d d1 0a 67 48 0f b9 3a eb 4a e8 38 3d 23 fd 48 8d 3d e1 7d d1 0a 67 48 0f b9 3a eb 37 e8 25 3d 23 fd 48 8d 3d de 7d d1 0a <67> 48 0f b9 3a eb 24 e8 12 3d 23 fd 48 8d 3d db 7d d1 0a 67 48 0f RSP: 0000:ffffc90000157948 EFLAGS: 00010246 RAX: ffffffff84a1301b RBX: 0000000000000003 RCX: ffff88801ca98000 RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffffffff8f72ae00 RBP: ffffffff99ae3b01 R08: ffff88801ca98000 R09: 0000000000000005 R10: 0000000000000100 R11: 0000000000000004 R12: ffff8880425ef568 R13: ffff8880425ef4f8 R14: ffff8880425ef578 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888126386000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7b46710e9c CR3: 000000000dbb6000 CR4: 00000000003526f0 Call Trace: __refcount_sub_and_test include/linux/refcount.h:400 [inline] __refcount_dec_and_test include/linux/refcount.h:432 [inline] refcount_dec_and_test include/linux/refcount.h:450 [inline] reqsk_put include/net/request_sock.h:136 [inline] __inet_csk_reqsk_queue_drop+0x3ce/0x440 net/ipv4/inet_connection_sock.c:1007 reqsk_timer_handler+0x651/0xdf0 net/ipv4/inet_connection_sock.c:1137 call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748 expire_timers kernel/time/timer.c:1799 [inline] __run_timers kernel/time/timer.c:2374 [inline] __run_timer_base+0x6a3/0x9f0 kernel/time/timer.c:2386 run_timer_base kernel/time/timer.c:2395 [inline] run_timer_softirq+0x67/0x170 kernel/time/timer.c:2403 handle_softirqs+0x1de/0x6d0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] run_ktimerd+0x69/0x100 kernel/softirq.c:1151 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
30%
KEV
Not listed

Published

June 25, 2026

Last Modified

July 24, 2026

Advisory Details (4)

Auto-updated Sep 5, 2026
No patch confirmed yet.
generic

tcp: Add preempt_{disable,enable}_nested() in reqsk_queue_hash_req(). - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/e10902df24488ca722303133acfc82490f7d59ad
generic

tcp: Add preempt_{disable,enable}_nested() in reqsk_queue_hash_req(). - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/de5a46f3b2c8d3cd20afa158bd3a725e3e3d6fd3
generic

tcp: Add preempt_{disable,enable}_nested() in reqsk_queue_hash_req(). - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/b183215ff714efb747d9d5a429322ba6404b5401
generic

tcp: Add preempt_{disable,enable}_nested() in reqsk_queue_hash_req(). - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/889fc99967007e2493833515a645cb2d800f6742

Vendor Advisories for CVE-2026-53260(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(7)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-virtual-hwe-26.04-edge (7.0.0-29.29) @ resolute2026-08-30ubuntu
ubuntulinux-tools-aws-edge (7.0.0-1010.10~24.04.1) @ noble2026-08-30ubuntu
ubuntulinux-virtual-hwe-24.04-edge (7.0.0-29.29~24.04.2) @ noble2026-08-30ubuntu
ubuntulinux-tools-gke-hwe-26.04 (7.0.0-1005.6) @ resolute2026-08-30ubuntu
ubuntulinux-tools-nvidia-hwe-24.04-edge (7.0.0-1016.16~24.04.1) @ noble2026-08-30ubuntu
ubuntulinux-tools-nvidia-hwe-26.04 (7.0.0-2016.16) @ resolute2026-08-30ubuntu
ubuntulinux-tools-oem-7.0 (7.0.0-1010.10) @ resolute2026-08-30ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFixed inDependents
linux-6.12—6.12.100-1~deb12u1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
linux6.12.38-1 ... 6.12.96-1 (31 versions)6.12.100-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
linux6.12.100-1 ... 7.0.9-1~bpo13+1 (145 versions)7.0.13-1—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(7)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 5× in last 7d / 165× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 471 total refreshes for this CVE.

  1. 2026-09-11 14:53 UTCEPSS rescore
  2. 2026-09-10 09:35 UTCEPSS rescore
  3. 2026-09-08 22:01 UTCEPSS rescore
  4. 2026-09-07 16:01 UTCEPSS rescore
  5. 2026-09-06 13:47 UTCEPSS rescore
  6. 2026-09-04 05:06 UTCEPSS rescore
  7. 2026-09-02 14:12 UTCEPSS rescore
  8. 2026-09-01 13:54 UTCEPSS rescore
  9. 2026-09-01 04:40 UTCEPSS rescore
  10. 2026-08-30 23:30 UTCVendor advisory
  11. 2026-08-30 23:30 UTCGHSA enrichment
  12. 2026-08-30 19:37 UTCEG score recompute
  13. 2026-08-30 19:37 UTCVendor advisory
  14. 2026-08-30 19:37 UTCGHSA enrichment
  15. 2026-08-30 19:17 UTCEPSS rescore
  16. 2026-08-30 01:22 UTCEPSS rescore
  17. 2026-08-28 21:41 UTCEPSS rescore
  18. 2026-08-28 03:40 UTCVendor advisory
  19. 2026-08-28 03:40 UTCGHSA enrichment
  20. 2026-08-27 23:57 UTCEG score recompute
  21. 2026-08-27 23:57 UTCVendor advisory
  22. 2026-08-27 23:57 UTCGHSA enrichment
  23. 2026-08-27 14:25 UTCEPSS rescore
  24. 2026-08-26 14:46 UTCEPSS rescore
  25. 2026-08-25 13:49 UTCEPSS rescore
Show 75 more
  1. 2026-08-25 05:15 UTCVendor advisory
  2. 2026-08-25 05:15 UTCGHSA enrichment
  3. 2026-08-25 01:33 UTCVendor advisory
  4. 2026-08-25 01:33 UTCGHSA enrichment
  5. 2026-08-24 21:52 UTCEG score recompute
  6. 2026-08-24 21:52 UTCVendor advisory
  7. 2026-08-24 21:52 UTCGHSA enrichment
  8. 2026-08-24 13:12 UTCEG score recompute
  9. 2026-08-24 13:12 UTCVendor advisory
  10. 2026-08-24 13:12 UTCGHSA enrichment
  11. 2026-08-24 04:31 UTCVendor advisory
  12. 2026-08-24 04:30 UTCGHSA enrichment
  13. 2026-08-23 23:11 UTCVendor advisory
  14. 2026-08-23 23:11 UTCGHSA enrichment
  15. 2026-08-23 18:54 UTCVendor advisory
  16. 2026-08-23 18:53 UTCGHSA enrichment
  17. 2026-08-23 15:11 UTCVendor advisory
  18. 2026-08-23 15:11 UTCGHSA enrichment
  19. 2026-08-23 11:29 UTCVendor advisory
  20. 2026-08-23 11:29 UTCGHSA enrichment
  21. 2026-08-23 07:45 UTCVendor advisory
  22. 2026-08-23 07:45 UTCGHSA enrichment
  23. 2026-08-23 02:11 UTCEG score recompute
  24. 2026-08-23 02:11 UTCVendor advisory
  25. 2026-08-23 02:11 UTCGHSA enrichment
  26. 2026-08-23 00:19 UTCEPSS rescore
  27. 2026-08-22 22:27 UTCVendor advisory
  28. 2026-08-22 22:27 UTCGHSA enrichment
  29. 2026-08-22 14:51 UTCVendor advisory
  30. 2026-08-22 14:51 UTCGHSA enrichment
  31. 2026-08-22 10:40 UTCVendor advisory
  32. 2026-08-22 10:40 UTCGHSA enrichment
  33. 2026-08-22 00:50 UTCEG score recompute
  34. 2026-08-22 00:50 UTCVendor advisory
  35. 2026-08-22 00:50 UTCGHSA enrichment
  36. 2026-08-21 23:49 UTCEPSS rescore
  37. 2026-08-21 21:08 UTCVendor advisory
  38. 2026-08-21 21:08 UTCGHSA enrichment
  39. 2026-08-21 17:26 UTCVendor advisory
  40. 2026-08-21 17:26 UTCGHSA enrichment
  41. 2026-08-21 12:51 UTCVendor advisory
  42. 2026-08-21 12:51 UTCGHSA enrichment
  43. 2026-08-21 09:08 UTCVendor advisory
  44. 2026-08-21 09:08 UTCGHSA enrichment
  45. 2026-08-21 05:09 UTCVendor advisory
  46. 2026-08-21 05:09 UTCGHSA enrichment
  47. 2026-08-20 23:22 UTCEG score recompute
  48. 2026-08-20 23:22 UTCVendor advisory
  49. 2026-08-20 23:22 UTCGHSA enrichment
  50. 2026-08-20 22:55 UTCEPSS rescore
  51. 2026-08-20 19:40 UTCVendor advisory
  52. 2026-08-20 19:40 UTCGHSA enrichment
  53. 2026-08-20 15:58 UTCVendor advisory
  54. 2026-08-20 15:58 UTCGHSA enrichment
  55. 2026-08-20 10:47 UTCVendor advisory
  56. 2026-08-20 10:47 UTCGHSA enrichment
  57. 2026-08-20 07:06 UTCEG score recompute
  58. 2026-08-20 07:06 UTCVendor advisory
  59. 2026-08-20 07:05 UTCGHSA enrichment
  60. 2026-08-19 17:04 UTCEPSS rescore
  61. 2026-08-19 14:14 UTCVendor advisory
  62. 2026-08-19 14:14 UTCGHSA enrichment
  63. 2026-08-19 10:29 UTCVendor advisory
  64. 2026-08-19 10:29 UTCGHSA enrichment
  65. 2026-08-19 05:42 UTCVendor advisory
  66. 2026-08-19 05:41 UTCGHSA enrichment
  67. 2026-08-19 01:30 UTCEG score recompute
  68. 2026-08-19 01:30 UTCVendor advisory
  69. 2026-08-19 01:30 UTCGHSA enrichment
  70. 2026-08-18 13:48 UTCEPSS rescore
  71. 2026-08-17 13:47 UTCEPSS rescore
  72. 2026-08-17 13:34 UTCVendor advisory
  73. 2026-08-17 13:34 UTCGHSA enrichment
  74. 2026-08-17 09:52 UTCVendor advisory
  75. 2026-08-17 09:52 UTCGHSA enrichment

Frequently asked(5)

What is CVE-2026-53260?
CVE-2026-53260 is a critical vulnerability published on June 25, 2026. In the Linux kernel, the following vulnerability has been resolved: tcp: Add preempt{disable,enable}nested() in reqskqueuehash_req(). syzbot reported a weird reqsk->rsk_refcnt underflow in inetcskreqskqueuedrop(). The captured reqskput() in inetcskreqskqueue_drop() is called only when it…
When was CVE-2026-53260 disclosed?
CVE-2026-53260 was first published in the National Vulnerability Database on June 25, 2026, with the most recent update on July 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-53260 actively exploited?
CVE-2026-53260 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 69.8% of all scored CVEs.
What is the CVSS score of CVE-2026-53260?
CVE-2026-53260 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-53260?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-53260, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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