CVE-2026-63918— Linux kernel 安全漏洞
一分钟漏洞结论
影响对象
Linux Linux
利用判断
尚无明确在野利用证据，仍需结合暴露面评估
建议动作
优先检查厂商安全公告和参考链接中的修复版本；无法立即升级时，限制受影响服务暴露并加强监测。
Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 6.12版本存在释放后重用漏洞，该漏洞源于l2tp_session_get_by_ifname()函数中未使用refcount_inc_not_zero()，导致引用计数为零的会话指针可能被返回，进而引发释放后重用。
可能的 ATT&CK 技术 1 AI
T1068 · Exploitation for Privilege Escalation影响版本矩阵 10
| 厂商 | 产品 | 版本范围 | 状态 |
|---|---|---|---|
| Linux | Linux | abe7a1a7d0b69e63b1bca5f9531023a52336784f< ee80455feffb9cb62b5b58715cabeff495e666b2 |
affected |
abe7a1a7d0b69e63b1bca5f9531023a52336784f< 947013fd7c8c35dd5856557b215840098a3f67f8 |
affected | ||
abe7a1a7d0b69e63b1bca5f9531023a52336784f< 782d60a6596aee9b29c2eecfa70033899278bf65 |
affected | ||
abe7a1a7d0b69e63b1bca5f9531023a52336784f< 05f95729ca844704d15e49ce14868af4b403b32b |
affected | ||
6.12 |
affected | ||
< 6.12 |
unaffected | ||
6.12.93≤ 6.12.* |
unaffected | ||
6.18.35≤ 6.18.* |
unaffected | ||
| … +2 条更多 | |||
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一、 漏洞 CVE-2026-63918 基础信息
漏洞信息
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Vulnerability Title
l2tp: use refcount_inc_not_zero in l2tp_session_get_by_ifname
来源: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
l2tp: use refcount_inc_not_zero in l2tp_session_get_by_ifname
A reader in l2tp_session_get_by_ifname() can return a pointer to a
session whose refcount has reached zero. The getter takes its
reference with plain refcount_inc(), but every other session getter
in the same file (l2tp_v2_session_get, l2tp_v3_session_get, and the
corresponding _get_next variants) uses refcount_inc_not_zero()
because the IDR/RCU lookup can race with refcount_dec_and_test() ->
l2tp_session_free() -> kfree_rcu(). The ifname getter is the only
outlier; the inconsistency was raised on-list after 979c017803c4
("l2tp: use list_del_rcu in l2tp_session_unhash").
A reader inside rcu_read_lock_bh() that matches session->ifname can
be preempted between the strcmp() and the refcount_inc(). If the
last reference drops on another CPU in that window, the reader's
refcount_inc() runs on a counter that has reached zero. refcount_t
catches the addition-on-zero, prints "refcount_t: addition on 0;
use-after-free", saturates the counter, and returns the saturated
pointer to the caller. Session memory is held live by the in-flight
RCU read section, but the kfree_rcu() callback queued from
l2tp_session_free() will free it once the grace period closes; a
caller that dereferences the returned session past that point hits
a slab-use-after-free. On PREEMPT_RT local_bh_disable() is a per-CPU
sleeping lock and the preemption window is real; on stock PREEMPT
kernels local_bh_disable() is a preempt_count increment that closes
the cross-CPU race in practice (see below).
Use refcount_inc_not_zero() and continue the list walk on failure,
matching the other session getters in the file. The ifname getter
is the only session getter in net/l2tp/ that still uses the bare
refcount_inc() pattern; this change restores file-internal
consistency. The success path is unchanged.
来源: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
来源: CVE Program / CVE List V5
Vulnerability Type
N/A
来源: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
来源: 中国国家信息安全漏洞库 CNNVD
Vulnerability Description
Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 6.12版本存在释放后重用漏洞，该漏洞源于l2tp_session_get_by_ifname()函数中未使用refcount_inc_not_zero()，导致引用计数为零的会话指针可能被返回，进而引发释放后重用。
来源: 中国国家信息安全漏洞库 CNNVD
CVSS Information
N/A
来源: 中国国家信息安全漏洞库 CNNVD
Vulnerability Type
N/A
来源: 中国国家信息安全漏洞库 CNNVD
受影响产品
二、漏洞 CVE-2026-63918 的公开POC
| # | POC 描述 | 源链接 | 神龙链接 |
|---|
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CVE-2026-63918 补丁与修复 (4)
同批安全公告 · Linux · 2026-07-19 · 共 429 条
| CVE-2026-63795 | 10.0 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64016 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-53398 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64136 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64037 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64035 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-63800 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64033 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64142 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-63808 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-63888 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64025 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-63887 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64089 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-63886 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64122 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64102 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-63984 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-63979 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-63993 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
显示前 20 条，共 429 条。 查看全部 → →
IV. Related Vulnerabilities
V. Comments for CVE-2026-63918
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