CVE-2023-53781

NONECVSS 0.0
0.0
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • No confirmed exploitation signals yet
CISA-KEV: Not listedEPSS: 0%CVSS: —Exploit: NoneExposed: 0

A fix is available — apply it.

In the Linux kernel, the following vulnerability has been resolved:

smc: Fix use-after-free in tcp_write_timer_handler().

With Eric's ref tracker, syzbot finally found a repro for use-after-free in tcp_write_timer_handler() by kernel TCP sockets. [0]

If SMC creates a kernel socket in __smc_create(), the kernel socket is supposed to be freed in smc_clcsock_release() by calling sock_release() when we close() the parent SMC socket.

However, at the end of smc_clcsock_release(), the kernel socket's sk_state might not be TCP_CLOSE. This means that we have not called inet_csk_destroy_sock() in __tcp_close() and have not stopped the TCP timers.

The kernel socket's TCP timers can be fired later, so we need to hold a refcnt for net as we do for MPTCP subflows in mptcp_subflow_create_socket().

[0]: leaked reference. sk_alloc (./include/net/net_namespace.h:335 net/core/sock.c:2108) inet_create (net/ipv4/af_inet.c:319 net/ipv4/af_inet.c:244) __sock_create (net/socket.c:1546) smc_create (net/smc/af_smc.c:3269 net/smc/af_smc.c:3284) __sock_create (net/socket.c:1546) __sys_socket (net/socket.c:1634 net/socket.c:1618 net/socket.c:1661) __x64_sys_socket (net/socket.c:1672) do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120) ================================================================== BUG: KASAN: slab-use-after-free in tcp_write_timer_handler (net/ipv4/tcp_timer.c:378 net/ipv4/tcp_timer.c:624 net/ipv4/tcp_timer.c:594) Read of size 1 at addr ffff888052b65e0d by task syzrepro/18091

CPU: 0 PID: 18091 Comm: syzrepro Tainted: G W 6.3.0-rc4-01174-gb5d54eb5899a #7 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.amzn2022.0.1 04/01/2014 Call Trace: dump_stack_lvl (lib/dump_stack.c:107) print_report (mm/kasan/report.c:320 mm/kasan/report.c:430) kasan_report (mm/kasan/report.c:538) tcp_write_timer_handler (net/ipv4/tcp_timer.c:378 net/ipv4/tcp_timer.c:624 net/ipv4/tcp_timer.c:594) tcp_write_timer (./include/linux/spinlock.h:390 net/ipv4/tcp_timer.c:643) call_timer_fn (./arch/x86/include/asm/jump_label.h:27 ./include/linux/jump_label.h:207 ./include/trace/events/timer.h:127 kernel/time/timer.c:1701) __run_timers.part.0 (kernel/time/timer.c:1752 kernel/time/timer.c:2022) run_timer_softirq (kernel/time/timer.c:2037) __do_softirq (./arch/x86/include/asm/jump_label.h:27 ./include/linux/jump_label.h:207 ./include/trace/events/irq.h:142 kernel/softirq.c:572) __irq_exit_rcu (kernel/softirq.c:445 kernel/softirq.c:650) irq_exit_rcu (kernel/softirq.c:664) sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1107 (discriminator 14))

CVSS v3
—
EG Score
0.0(none)
EPSS
5.8%
KEV
Not listed

Published

December 9, 2025

Last Modified

April 15, 2026

References (2)

Vendor Advisories for CVE-2023-53781(3)

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

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatkernel-0:5.14.0-611.5.1.el9_72025-11-11redhat
linuxKernel @ 6.2.12—osv

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.

Data Freshness Timeline

(refreshed 11× in last 7d / 45× 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 116 total refreshes for this CVE.

  1. 2026-07-22 14:07 UTCEPSS rescore
  2. 2026-07-22 14:07 UTCEPSS rescore
  3. 2026-07-21 15:23 UTCEPSS rescore
  4. 2026-07-20 17:06 UTCEPSS rescore
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  20. 2026-07-11 08:26 UTCEPSS rescore
  21. 2026-07-10 00:45 UTCOSV refresh
  22. 2026-07-09 19:08 UTCEPSS rescore
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  24. 2026-07-07 13:45 UTCEPSS rescore
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  1. 2026-07-06 16:26 UTCEPSS rescore
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  5. 2026-07-05 02:29 UTCEPSS rescore
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  7. 2026-07-01 15:05 UTCEPSS rescore
  8. 2026-06-30 23:21 UTCEPSS rescore
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  10. 2026-06-29 14:05 UTCEPSS rescore
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  23. 2026-06-21 14:55 UTCEPSS rescore
  24. 2026-06-21 14:55 UTCEPSS rescore
  25. 2026-06-21 11:01 UTCOSV refresh
  26. 2026-06-21 01:58 UTCEPSS rescore
  27. 2026-06-21 01:58 UTCEPSS rescore
  28. 2026-06-19 19:24 UTCEPSS rescore
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  30. 2026-06-18 17:51 UTCEPSS rescore
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  39. 2026-06-11 13:59 UTCEPSS rescore
  40. 2026-06-10 22:17 UTCEPSS rescore
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  42. 2026-06-08 14:16 UTCEPSS rescore
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  44. 2026-06-07 15:24 UTCEPSS rescore
  45. 2026-06-07 15:24 UTCEPSS rescore
  46. 2026-06-06 13:46 UTCEPSS rescore
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  48. 2026-06-05 22:46 UTCEPSS rescore
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  50. 2026-06-05 06:09 UTCEPSS rescore
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  52. 2026-06-04 13:11 UTCEPSS rescore
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  54. 2026-06-02 20:12 UTCEPSS rescore
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  56. 2026-06-02 02:39 UTCOSV refresh
  57. 2026-06-01 13:51 UTCEPSS rescore
  58. 2026-05-31 22:30 UTCEPSS rescore
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Frequently asked(4)

What is CVE-2023-53781?
CVE-2023-53781 is a none vulnerability published on December 9, 2025. In the Linux kernel, the following vulnerability has been resolved: smc: Fix use-after-free in tcpwritetimer_handler(). With Eric's ref tracker, syzbot finally found a repro for use-after-free in tcpwritetimer_handler() by kernel TCP sockets. [0] If SMC creates a kernel socket in smc_create(), the…
When was CVE-2023-53781 disclosed?
CVE-2023-53781 was first published in the National Vulnerability Database on December 9, 2025, with the most recent update on April 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2023-53781 actively exploited?
CVE-2023-53781 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 5.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
How do I remediate CVE-2023-53781?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2023-53781, 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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