Linux Kernel: IPC ID Allocation Out of Bounds Causes IDR Corruption
CVE-2026-52923 Published on June 24, 2026

ipc: limit next_id allocation to the valid ID range
In the Linux kernel, the following vulnerability has been resolved: ipc: limit next_id allocation to the valid ID range The checkpoint/restore sysctl path can request the next SysV IPC id through ids->next_id. ipc_idr_alloc() currently forwards that request to idr_alloc() with an open-ended upper bound. If the valid tail of the SysV IPC id space is full, the allocation can spill beyond ipc_mni. The returned SysV IPC id still uses the normal index encoding, so later lookup and removal can target the wrong slot. This leaves the real IDR entry behind and breaks the IDR state for the object. The bug is in ipc_idr_alloc() in the checkpoint/restore path. 1. ids->next_id is passed to: idr_alloc(&ids->ipcs_idr, new, ipcid_to_idx(next_id), 0, ...) 2. The zero upper bound makes the allocation effectively open-ended. Once the valid SysV IPC tail is occupied, idr_alloc() can spill past ipc_mni and allocate an entry beyond the valid IPC id range. 3. The new object id is still encoded with the narrower SysV IPC index width: new->id = (new->seq << ipcmni_seq_shift()) + idx 4. Later removal goes through ipc_rmid(), which uses: ipcid_to_idx(ipcp->id) That truncates the real IDR index. An object actually stored at a high index can then be removed as if it lived at a low in-range index. 5. For shared memory, shm_destroy() frees the current object anyway, but the real high IDR slot is left behind as a dangling pointer. 6. A subsequent walk of /proc/sysvipc/shm reaches the stale IDR entry and dereferences freed memory. Prevent this by bounding the requested allocation to ipc_mni so the checkpoint/restore path fails once the valid range is exhausted.

NVD

Vulnerability Analysis

CVE-2026-52923 can be exploited with local system access, and requires small amount of user privileges. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and a high impact on availability.

Attack Vector:

LOCAL

Attack Complexity:

HIGH

Privileges Required:

LOW

User Interaction:

NONE

Scope:

UNCHANGED

Confidentiality Impact:

LOW

Integrity Impact:

LOW

Availability Impact:

HIGH

Weakness Type

What is a Dangling pointer Vulnerability?

The program dereferences a pointer that contains a location for memory that was previously valid, but is no longer valid. When a program releases memory, but it maintains a pointer to that memory, then the memory might be re-allocated at a later time. If the original pointer is accessed to read or write data, then this could cause the program to read or modify data that is in use by a different function or process. Depending on how the newly-allocated memory is used, this could lead to a denial of service, information exposure, or code execution.

CVE-2026-52923 has been classified to as a Dangling pointer vulnerability or weakness.

Products Associated with CVE-2026-52923

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Linux Kernel

Red Hat Enterprise Linux (RHEL)

Canonical Ubuntu Linux

Red Hat Rhel Aus

Red Hat Rhel Eus Long Life

Red Hat Rhel E4s

Red Hat Rhel Eus

Affected Versions

Linux:

Version 03f595668017f1a1fb971c02fc37140bc6e7bb1c and below 3bbe2bb9111ce6967a951bfac79af142d816fae5 is affected.
Version 03f595668017f1a1fb971c02fc37140bc6e7bb1c and below 8c58a92849175f5e2ab7bc2734b3b89afe79f6ef is affected.
Version 03f595668017f1a1fb971c02fc37140bc6e7bb1c and below af24e202b543ded8a34f1d5d3db54eb916173f04 is affected.
Version 03f595668017f1a1fb971c02fc37140bc6e7bb1c and below 157ce2c6836ce0ff19108a819f38df061345425f is affected.
Version 03f595668017f1a1fb971c02fc37140bc6e7bb1c and below 41058d4c3f63ab64901560a704882e0565f4e456 is affected.
Version 03f595668017f1a1fb971c02fc37140bc6e7bb1c and below a3cc795129e5ec0f8948653a3bf471e7d8852f5e is affected.
Version 03f595668017f1a1fb971c02fc37140bc6e7bb1c and below bd4be70669af55b974860d13680348cfdf50bbed is affected.
Version 03f595668017f1a1fb971c02fc37140bc6e7bb1c and below fa0b9b2b7ae3539908d69c2b9ac0d144d9bc5139 is affected.

Linux:

Version 3.8 is affected.
Before 3.8 is unaffected.
Version 5.10.259, <= 5.10.* is unaffected.
Version 5.15.210, <= 5.15.* is unaffected.
Version 6.1.176, <= 6.1.* is unaffected.
Version 6.6.143, <= 6.6.* is unaffected.
Version 6.12.93, <= 6.12.* is unaffected.
Version 6.18.35, <= 6.18.* is unaffected.
Version 7.0.12, <= 7.0.* is unaffected.
Version 7.1, <= * is unaffected.

Red Hat Enterprise Linux 8:

Version 0:4.18.0-553.151.1.rt7.492.el8_10 and below * is unaffected.

Red Hat Enterprise Linux 8:

Version 0:4.18.0-553.151.1.el8_10 and below * is unaffected.

Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support:

Version 0:4.18.0-305.200.1.el8_4 and below * is unaffected.

Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On:

Version 0:4.18.0-305.200.1.el8_4 and below * is unaffected.

Red Hat Enterprise Linux 9:

Version 0:5.14.0-687.33.1.el9_8 and below * is unaffected.

Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions:

Version 0:5.14.0-427.141.1.el9_4 and below * is unaffected.

Red Hat Enterprise Linux 9.6 Extended Update Support:

Version 0:5.14.0-570.131.1.el9_6 and below * is unaffected.

Red Hat Enterprise Linux 10: Red Hat Enterprise Linux 6: Red Hat Enterprise Linux 7: Red Hat Enterprise Linux 7: Red Hat Enterprise Linux 9:

Exploit Probability

EPSS

0.13%

Percentile

2.98%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.