CVE-2026-23195

Status: ModifiedHigh (7.8)—

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

cgroup/dmem: avoid pool UAF

An UAF issue was observed:

The issue occurs because a pool can still be held by a caller after its associated memory region is unregistered. The current implementation frees the pool even if users still hold references to it (e.g., before uncharge operations complete).

This patch adds a reference counter to each pool, ensuring that a pool is only freed when its reference count drops to zero.

Technical details traces, logs and code from the original report

BUG: KASAN: slab-use-after-free in page_counter_uncharge+0x65/0x150
Write of size 8 at addr ffff888106715440 by task insmod/527

CPU: 4 UID: 0 PID: 527 Comm: insmod    6.19.0-rc7-next-20260129+ #11
Tainted: [O]=OOT_MODULE
Call Trace:
<TASK>
dump_stack_lvl+0x82/0xd0
kasan_report+0xca/0x100
kasan_check_range+0x39/0x1c0
page_counter_uncharge+0x65/0x150
dmem_cgroup_uncharge+0x1f/0x260

Allocated by task 527:

Freed by task 0:

The buggy address belongs to the object at ffff888106715400
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 64 bytes inside of
freed 512-byte region [ffff888106715400, ffff888106715600)

The buggy address belongs to the physical page:

Memory state around the buggy address:
ffff888106715300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888106715380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888106715400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
				     ^
ffff888106715480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888106715500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

CVSS

Version: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Base score: 7.8

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.12%
Percentile among all scored CVEs: 2
Score date: 10/6/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

🎯 ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

ExploitationT1068 Exploitation for Privilege Escalationprivilege escalation75 %
Primary impactT1059 Command and Scripting Interpreterexecution60 %

AV:L, PR:L sin UI permite escalada local; UAF en kernel puede llevar a ejecución de código arbitrario con contexto privilegiado (root).

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

🛡️ ATT&CK mitigations that cover these techniques

Execution Prevention Threat Intelligence Program Restrict Web-Based Content Privileged Account Management Limit Software Installation Behavior Prevention on Endpoint

Affected technologies (1)

Linux — Linux Kernel

CWEs

CWE-416

References

Raw JSON (NVD)

Show

{
  "id": "CVE-2026-23195",
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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncgroup/dmem: avoid pool UAF\n\nAn UAF issue was observed:\n\nBUG: KASAN: slab-use-after-free in page_counter_uncharge+0x65/0x150\nWrite of size 8 at addr ffff888106715440 by task insmod/527\n\nCPU: 4 UID: 0 PID: 527 Comm: insmod    6.19.0-rc7-next-20260129+ #11\nTainted: [O]=OOT_MODULE\nCall Trace:\n<TASK>\ndump_stack_lvl+0x82/0xd0\nkasan_report+0xca/0x100\nkasan_check_range+0x39/0x1c0\npage_counter_uncharge+0x65/0x150\ndmem_cgroup_uncharge+0x1f/0x260\n\nAllocated by task 527:\n\nFreed by task 0:\n\nThe buggy address belongs to the object at ffff888106715400\nwhich belongs to the cache kmalloc-512 of size 512\nThe buggy address is located 64 bytes inside of\nfreed 512-byte region [ffff888106715400, ffff888106715600)\n\nThe buggy address belongs to the physical page:\n\nMemory state around the buggy address:\nffff888106715300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc\nffff888106715380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc\n>ffff888106715400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n\t\t\t\t     ^\nffff888106715480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\nffff888106715500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n\nThe issue occurs because a pool can still be held by a caller after its\nassociated memory region is unregistered. The current implementation frees\nthe pool even if users still hold references to it (e.g., before uncharge\noperations complete).\n\nThis patch adds a reference counter to each pool, ensuring that a pool is\nonly freed when its reference count drops to zero."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\ncgroup/dmem: evitar UAF de pool\n\nSe observó un problema de UAF:\n\nERROR: KASAN: slab-uso después de liberación en page_counter_uncharge+0x65/0x150\nEscritura de tamaño 8 en addr ffff888106715440 por la tarea insmod/527\n\nCPU: 4 UID: 0 PID: 527 Comm: insmod    6.19.0-rc7-next-20260129+ #11\nTainted: [O]=OOT_MODULE\nTraza de Llamada:\n\ndump_stack_lvl+0x82/0xd0\nkasan_report+0xca/0x100\nkasan_check_range+0x39/0x1c0\npage_counter_uncharge+0x65/0x150\ndmem_cgroup_uncharge+0x1f/0x260\n\nAsignado por la tarea 527:\n\nLiberado por la tarea 0:\n\nLa dirección errónea pertenece al objeto en ffff888106715400\nque pertenece a la caché kmalloc-512 de tamaño 512\nLa dirección errónea está ubicada 64 bytes dentro de\nregión liberada de 512 bytes [ffff888106715400, ffff888106715600)\n\nLa dirección errónea pertenece a la página física:\n\nEstado de la memoria alrededor de la dirección errónea:\nffff888106715300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc\nffff888106715380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc\n&gt;ffff888106715400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n\t\t\t\t     ^\nffff888106715480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\nffff888106715500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n\nEl problema ocurre porque un pool aún puede ser retenido por un llamador después de que su región de memoria asociada es desregistrada. La implementación actual libera el pool incluso si los usuarios aún mantienen referencias a él (p. ej., antes de que las operaciones de descarga se completen).\n\nEste parche añade un contador de referencias a cada pool, asegurando que un pool solo se libera cuando su contador de referencias llega a cero."
    }
  ],
  "lastModified": "2026-06-17T10:21:04.633",
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