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🛡️ CVE-2023-53121 — kernel

🟡 CVSS 5.5 — Medium ✅ No Known Exploit NVD
5.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

tcp: tcp_make_synack() can be called from process context

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

tcp: tcp_make_synack() can be called from process context

tcp_rtx_synack() now could be called in process context as explained in

0a375c822497 ("tcp: tcp_rtx_synack() can be called from process

context").

tcp_rtx_synack() might call tcp_make_synack(), which will touch per-CPU

variables with preemption enabled. This causes the following BUG:

BUG: using __this_cpu_add() in preemptible [00000000] code: ThriftIO1/5464

caller is tcp_make_synack+0x841/0xac0

Call Trace:

<TASK>

dump_stack_lvl+0x10d/0x1a0

check_preemption_disabled+0x104/0x110

tcp_make_synack+0x841/0xac0

tcp_v6_send_synack+0x5c/0x450

tcp_rtx_synack+0xeb/0x1f0

inet_rtx_syn_ack+0x34/0x60

tcp_check_req+0x3af/0x9e0

tcp_rcv_state_process+0x59b/0x2030

tcp_v6_do_rcv+0x5f5/0x700

release_sock+0x3a/0xf0

tcp_sendmsg+0x33/0x40

____sys_sendmsg+0x2f2/0x490

__sys_sendmsg+0x184/0x230

do_syscall_64+0x3d/0x90

Avoid calling __TCP_INC_STATS() with will touch per-cpu variables. Use

TCP_INC_STATS() which is safe to be called from context switch.

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

  • Attack vector: Local — a local account, shell or session on the host is needed.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: Low — an ordinary user account is enough.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: None.
  • Integrity impact: None.
  • Availability impact: High — total loss, or loss the attacker controls.

Affected software

CVE-2023-53121 is recorded against 2 packages.

  • kernel (from 6.2.0 up to 6.2.8)
  • linux-kernel

Timeline and source

Published on 2 May 2025 and last revised on 12 August 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
github.com (Advisory)
nvd.nist.gov (Advisory)
git.kernel.org (Package)

Other advisories for this package

kernel has other advisories on record. If you are patching this one, these are worth checking on the same host:

CVE-2023-53121 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Medium
CVSS Score 5.5
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2025-05-02
Updated 2026-08-20
Modified 2026-08-12

Affected Packages

Software From version Fixed in
kernel 6.2.0 6.2.8
linux-kernel — —

References

Similar Threats

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