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CVE-2026-23127— perf: Fix refcount warning on event->mmap_count increment

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中对event->mmap_count的引用计数操作不当，可能导致使用后释放警告。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.12% · P2

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux 448f97fba9013ffa13f5dd82febd18836b189499< 23c0e4bd93d0b250775162faf456470485ac9fc7 affected
448f97fba9013ffa13f5dd82febd18836b189499< d06bf78e55d5159c1b00072e606ab924ffbbad35 affected
6.18 affected
< 6.18 unaffected
6.18.8≤ 6.18.* unaffected
6.19≤ * unaffected
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I. Basic Information for CVE-2026-23127

Vulnerability Information
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Vulnerability Title
perf: Fix refcount warning on event->mmap_count increment
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: perf: Fix refcount warning on event->mmap_count increment When calling refcount_inc(&event->mmap_count) inside perf_mmap_rb(), the following warning is triggered: refcount_t: addition on 0; use-after-free. WARNING: lib/refcount.c:25 PoC: struct perf_event_attr attr = {0}; int fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, 0); mmap(NULL, 0x3000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); int victim = syscall(__NR_perf_event_open, &attr, 0, -1, fd, PERF_FLAG_FD_OUTPUT); mmap(NULL, 0x3000, PROT_READ | PROT_WRITE, MAP_SHARED, victim, 0); This occurs when creating a group member event with the flag PERF_FLAG_FD_OUTPUT. The group leader should be mmap-ed and then mmap-ing the event triggers the warning. Since the event has copied the output_event in perf_event_set_output(), event->rb is set. As a result, perf_mmap_rb() calls refcount_inc(&event->mmap_count) when event->mmap_count = 0. Disallow the case when event->mmap_count = 0. This also prevents two events from updating the same user_page.
Source: CVE Program / CVE List V5
CVSS Information
N/A
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中对event->mmap_count的引用计数操作不当，可能导致使用后释放警告。
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 448f97fba9013ffa13f5dd82febd18836b189499 ~ 23c0e4bd93d0b250775162faf456470485ac9fc7 -
Linux Linux 6.18 -

II. Public POCs for CVE-2026-23127

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III. Intelligence Information for CVE-2026-23127

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Same Patch Batch · Linux · 2026-02-14 · 108 CVEs total

CVE-2025-71202 8.8 HIGH iommu/sva: invalidate stale IOTLB entries for kernel address space
CVE-2026-23193 8.8 HIGH scsi: target: iscsi: Fix use-after-free in iscsit_dec_session_usage_count()
CVE-2026-23172 8.4 HIGH net: wwan: t7xx: fix potential skb->frags overflow in RX path
CVE-2026-23191 7.8 HIGH ALSA: aloop: Fix racy access at PCM trigger
CVE-2025-71221 7.8 HIGH dmaengine: mmp_pdma: Fix race condition in mmp_pdma_residue()
CVE-2026-23178 7.8 HIGH HID: i2c-hid: fix potential buffer overflow in i2c_hid_get_report()
CVE-2026-23184 7.8 HIGH binder: fix UAF in binder_netlink_report()
CVE-2026-23185 7.8 HIGH wifi: iwlwifi: mld: cancel mlo_scan_start_wk
CVE-2026-23171 7.8 HIGH bonding: fix use-after-free due to enslave fail after slave array update
CVE-2026-23169 7.8 HIGH mptcp: fix race in mptcp_pm_nl_flush_addrs_doit()
CVE-2026-23192 7.8 HIGH linkwatch: use __dev_put() in callers to prevent UAF
CVE-2026-23209 7.8 HIGH macvlan: fix error recovery in macvlan_common_newlink()
CVE-2026-23198 7.8 HIGH KVM: Don't clobber irqfd routing type when deassigning irqfd
CVE-2026-23139 7.5 HIGH netfilter: nf_conncount: update last_gc only when GC has been performed
CVE-2026-23136 7.5 HIGH libceph: reset sparse-read state in osd_fault()
CVE-2026-23148 7.5 HIGH nvmet: fix race in nvmet_bio_done() leading to NULL pointer dereference
CVE-2025-71204 7.5 HIGH smb/server: fix refcount leak in parse_durable_handle_context()
CVE-2026-23161 7.3 HIGH mm/shmem, swap: fix race of truncate and swap entry split
CVE-2025-71201 7.1 HIGH netfs: Fix early read unlock of page with EOF in middle
CVE-2026-23204 7.1 HIGH net/sched: cls_u32: use skb_header_pointer_careful()

Showing top 20 of 108 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-23127

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