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CVE-2026-23248— perf/core: Fix refcount bug and potential UAF in perf_mmap

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于perf_mmap函数中存在竞争条件，可能导致释放后重用或引用计数错误。

CVSS 7.8 · High EPSS 0.10% · P1

Possible ATT&CK Techniques 1 AI

T1055 · Process Injection

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux b709eb872e19a19607bbb6d2975bc264d59735cf< c27dea9f50ed525facb62ef647dddc4722456e07 affected
b709eb872e19a19607bbb6d2975bc264d59735cf< ac7ecb65af170a7fc193e7bd8be15dac84ec6a56 affected
b709eb872e19a19607bbb6d2975bc264d59735cf< 77de62ad3de3967818c3dbe656b7336ebee461d2 affected
6.14 affected
< 6.14 unaffected
6.18.17≤ 6.18.* unaffected
6.19.7≤ 6.19.* unaffected
7.0≤ * unaffected
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I. Basic Information for CVE-2026-23248

Vulnerability Information
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Vulnerability Title
perf/core: Fix refcount bug and potential UAF in perf_mmap
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: perf/core: Fix refcount bug and potential UAF in perf_mmap Syzkaller reported a refcount_t: addition on 0; use-after-free warning in perf_mmap. The issue is caused by a race condition between a failing mmap() setup and a concurrent mmap() on a dependent event (e.g., using output redirection). In perf_mmap(), the ring_buffer (rb) is allocated and assigned to event->rb with the mmap_mutex held. The mutex is then released to perform map_range(). If map_range() fails, perf_mmap_close() is called to clean up. However, since the mutex was dropped, another thread attaching to this event (via inherited events or output redirection) can acquire the mutex, observe the valid event->rb pointer, and attempt to increment its reference count. If the cleanup path has already dropped the reference count to zero, this results in a use-after-free or refcount saturation warning. Fix this by extending the scope of mmap_mutex to cover the map_range() call. This ensures that the ring buffer initialization and mapping (or cleanup on failure) happens atomically effectively, preventing other threads from accessing a half-initialized or dying ring buffer.
Source: 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
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于perf_mmap函数中存在竞争条件，可能导致释放后重用或引用计数错误。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux b709eb872e19a19607bbb6d2975bc264d59735cf ~ c27dea9f50ed525facb62ef647dddc4722456e07 -
Linux Linux 6.14 -

II. Public POCs for CVE-2026-23248

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III. Intelligence Information for CVE-2026-23248

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Patches & Fixes for CVE-2026-23248 (3)

Same Patch Batch · Linux · 2026-03-18 · 35 CVEs total

CVE-2026-23246 8.8 HIGH wifi: mac80211: bounds-check link_id in ieee80211_ml_reconfiguration
CVE-2026-23268 7.8 HIGH apparmor: fix unprivileged local user can do privileged policy management
CVE-2026-23270 7.8 HIGH net/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks
CVE-2026-23253 7.8 HIGH media: dvb-core: fix wrong reinitialization of ringbuffer on reopen
CVE-2026-23243 7.8 HIGH RDMA/umad: Reject negative data_len in ib_umad_write
CVE-2026-23245 7.8 HIGH net/sched: act_gate: snapshot parameters with RCU on replace
CVE-2025-71269 7.5 HIGH btrfs: do not free data reservation in fallback from inline due to -ENOSPC
CVE-2025-71268 7.5 HIGH btrfs: fix reservation leak in some error paths when inserting inline extent
CVE-2026-23242 7.5 HIGH RDMA/siw: Fix potential NULL pointer dereference in header processing
CVE-2026-23269 7.1 HIGH apparmor: validate DFA start states are in bounds in unpack_pdb
CVE-2026-23244 nvme: fix memory allocation in nvme_pr_read_keys()
CVE-2026-23247 tcp: secure_seq: add back ports to TS offset
CVE-2026-23249 xfs: check for deleted cursors when revalidating two btrees
CVE-2026-23250 xfs: check return value of xchk_scrub_create_subord
CVE-2026-23251 xfs: only call xf{array,blob}_destroy if we have a valid pointer
CVE-2026-23252 xfs: get rid of the xchk_xfile_*_descr calls
CVE-2025-71267 fs: ntfs3: fix infinite loop triggered by zero-sized ATTR_LIST
CVE-2025-71266 fs: ntfs3: check return value of indx_find to avoid infinite loop
CVE-2025-71265 fs: ntfs3: fix infinite loop in attr_load_runs_range on inconsistent metadata
CVE-2025-71270 LoongArch: Enable exception fixup for specific ADE subcode

Showing top 20 of 35 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-23248

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