CVE-2026-23127
published 2026-02-14CVE-2026-23127: In the Linux kernel, the following vulnerability has been resolved: perf: Fix refcount warning on event->mmap_count increment When calling…
PriorityP420medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.10%
1.2th percentile
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.
Affected
7 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | linux | < linux 6.18.8-1 (forky) | linux 6.18.8-1 (forky) |
| linux | linux | — | — |
| linux | linux | >= 448f97fba9013ffa13f5dd82febd18836b189499 < 23c0e4bd93d0b250775162faf456470485ac9fc7 | 23c0e4bd93d0b250775162faf456470485ac9fc7 |
| linux | linux | >= 448f97fba9013ffa13f5dd82febd18836b189499 < d06bf78e55d5159c1b00072e606ab924ffbbad35 | d06bf78e55d5159c1b00072e606ab924ffbbad35 |
| linux | linux_kernel | — | — |
| linux | linux_kernel | >= 0 < 6.18.8-1 | 6.18.8-1 |
| linux | linux_kernel | >= 6.18 < 6.18.8 | 6.18.8 |
CVSS provenance
nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv5.5MEDIUM
vendor_debian5.5LOW
vendor_redhat5.5MEDIUM
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Red Hat
kernel: Linux kernel: Privilege escalation or denial of service in perf subsystem
vendor_redhat·2026-02-14·CVSS 5.5
CVE-2026-23127 [MEDIUM] CWE-911 kernel: Linux kernel: Privilege escalation or denial of service in perf subsystem
kernel: Linux kernel: Privilege escalation or denial of service in perf subsystem
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 sho
Debian
CVE-2026-23127: linux - In the Linux kernel, the following vulnerability has been resolved: perf: Fix r...
vendor_debian·2026·CVSS 5.5
CVE-2026-23127 [MEDIUM] CVE-2026-23127: linux - In the Linux kernel, the following vulnerability has been resolved: perf: Fix r...
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 ha
OSV
CVE-2026-23127: In the Linux kernel, the following vulnerability has been resolved: perf: Fix refcount warning on event->mmap_count increment When calling refcount_in
osv·2026-02-14·CVSS 5.5
CVE-2026-23127 [MEDIUM] CVE-2026-23127: In the Linux kernel, the following vulnerability has been resolved: perf: Fix refcount warning on event->mmap_count increment When calling refcount_in
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 ha
GHSA
GHSA-5pm5-3fx7-4f4r: In the Linux kernel, the following vulnerability has been resolved:
perf: Fix refcount warning on event->mmap_count increment
When calling refcount_
ghsa_unreviewed·2026-02-14
CVE-2026-23127 [MEDIUM] GHSA-5pm5-3fx7-4f4r: In the Linux kernel, the following vulnerability has been resolved:
perf: Fix refcount warning on event->mmap_count increment
When calling refcount_
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 e
No detection rules found.
No public exploits indexed.
Bugzilla
CVE-2026-23127 kernel: Linux kernel: Privilege escalation or denial of service in perf subsystem
bugzilla·2026-02-14·CVSS 5.5
CVE-2026-23127 [MEDIUM] CVE-2026-23127 kernel: Linux kernel: Privilege escalation or denial of service in perf subsystem
CVE-2026-23127 kernel: Linux kernel: Privilege escalation or denial of service in perf subsystem
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.
Wiz
CVE-2026-23127 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 5.5
CVE-2026-23127 [MEDIUM] CVE-2026-23127 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2026-23127 :
Linux Kernel vulnerability analysis and mitigation
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
2026-02-14
Published