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Unity Linux 20.1050a Security Update: kernel (UTSA-2026-100765)
medium Nessus Plugin ID 336991
Synopsis
The Unity Linux host is missing one or more security updates.Description
The Unity Linux 20 host has a package installed that is affected by a vulnerability as referenced in the UTSA-2026-100765 advisory.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.
Tenable has extracted the preceding description block directly from the Unity Linux security advisory.
Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.
Solution
Update the affected kernel package.See Also
https://nvd.nist.gov/vuln/detail/CVE-2026-52923
Plugin Details
Severity: Medium
ID: 336991
File Name: unity_linux_UTSA-2026-100765.nasl
Version: 1.1
Type: Local
Published: 8/17/2026
Updated: 8/17/2026
Supported Sensors: Nessus
Risk Information
VPR
Risk Factor: Medium
Score: 6.6
Percentile: 96.9
CVSS v2
Risk Factor: Medium
Base Score: 6.8
Temporal Score: 5
Vector: CVSS2#AV:L/AC:L/Au:S/C:C/I:C/A:C
CVSS Score Source: CVE-2026-52923
CVSS v3
Risk Factor: Medium
Base Score: 5.8
Temporal Score: 5.1
Vector: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H
Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C
Vulnerability Information
Required KB Items: Host/local_checks_enabled, Host/cpu, Host/UOS-Server/release, Host/UOS-Server/rpm-list
Exploit Ease: No known exploits are available
Patch Publication Date: 8/13/2026
Vulnerability Publication Date: 6/24/2026
Reference Information
CVE: CVE-2026-52923