Linux Kernel up to 6.18.49/7.2.3 fanotify fanotify_read ppos use after free

CVSS Meta Temp Score
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CTI Interest Score
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9.5$5k-$25k0.84+

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.18.49/7.2.3. It has been classified as very critical. Affected by this vulnerability is the function fanotify_read of the component fanotify. Performing a manipulation of the argument ppos results in use after free. This vulnerability is reported as CVE-2026-89600. The attack is possible to be carried out remotely. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as very critical, was found in Linux Kernel up to 6.18.49/7.2.3. This affects the function fanotify_read of the component fanotify. The manipulation of the argument ppos with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: fanotify: fix use-after-free of file range info fsnotify_pre_content() builds its file_range on the triggering task's stack. fanotify_alloc_perm_event() saves a pointer to range.pos in the heap-allocated permission event so copy_range_info_to_user() can report the offset later. The event reader can set the event state to FAN_EVENT_REPORTED and then sleep while preparing the file descriptor. If a signal interrupts the triggering task at that point, fanotify_get_response() changes the state to FAN_EVENT_CANCELED and returns. This unwinds the file_range stack frame while the reader still owns the event. The reader then dereferences pevent->ppos and copies the stale stack value to userspace. KASAN reported: BUG: KASAN: use-after-free in fanotify_read+0x293e/0x2970 Read of size 8 at addr ffff88811434fc50 by task fanotify_inotif/95 Call Trace: fanotify_read+0x293e/0x2970 vfs_read+0x177/0xa20 ksys_read+0xf7/0x1c0 do_syscall_64+0xf9/0x540 entry_SYSCALL_64_after_hwframe+0x77/0x7f Store the range position directly in the permission event and use FANOTIFY_NO_RANGE when range information is unavailable. The event remains alive until the reader finishes, so the reported offset no longer depends on the triggering task's stack.

The advisory is shared at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-89600 since 09/11/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details are known, but no exploit is available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 09/12/2026).

Upgrading to version 6.18.50, 7.2.4 or 7.3-rc1 eliminates this vulnerability. Applying the patch 66aa9a9e6481bfa512ee5b6380eaaec455a954d2/b8f73b163b646bc56d4dce9c697a578e333f4894/d7f1cf5be33ef0175a4e8ed8687aeb98fb00a851 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

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Version

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 9.9
VulDB Meta Temp Score: 9.5

VulDB Base Score: 9.9
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.18.50/7.2.4/7.3-rc1
Patch: 66aa9a9e6481bfa512ee5b6380eaaec455a954d2/b8f73b163b646bc56d4dce9c697a578e333f4894/d7f1cf5be33ef0175a4e8ed8687aeb98fb00a851

Timelineinfo

09/11/2026 CVE reserved
09/11/2026 +0 days VulDB entry created
09/12/2026 +0 days Advisory disclosed
09/12/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-89600 (🔒)
GCVE (CVE): GCVE-0-2026-89600
GCVE (VulDB): GCVE-100-402897

Entryinfo

Created: 09/12/2026 01:35
Changes: 09/12/2026 01:35 (60)
Complete: 🔍
Cache ID: 216::103

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