CVE-2026-52923: Linux kernel · ipc: limit next_id allocation to the valid ID range
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 7.8 High · fixed in fa0b9b2b7ae3539908d69c2b9ac0d144d9bc5139 : patch Linux kernel soon.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Total control over the software or total information disclosure
CISA SSVC assessment, 2026-10-16.
- Patch
- Available – fixed in fa0b9b2b7ae3539908d69c2b9ac0d144d9bc5139, bd4be70669af55b974860d13680348cfdf50bbed, af24e202b543ded8a34f1d5d3db54eb916173f04 +5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 24 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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Description
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.
References
- git.kernel.org/stable/c/3bbe2bb9111ce6967a951bfac79af142d816fae5 (opens in a new tab)
- git.kernel.org/stable/c/8c58a92849175f5e2ab7bc2734b3b89afe79f6ef (opens in a new tab)
- git.kernel.org/stable/c/af24e202b543ded8a34f1d5d3db54eb916173f04 (opens in a new tab)
- git.kernel.org/stable/c/157ce2c6836ce0ff19108a819f38df061345425f (opens in a new tab)
- git.kernel.org/stable/c/41058d4c3f63ab64901560a704882e0565f4e456 (opens in a new tab)
- git.kernel.org/stable/c/a3cc795129e5ec0f8948653a3bf471e7d8852f5e (opens in a new tab)
- git.kernel.org/stable/c/bd4be70669af55b974860d13680348cfdf50bbed (opens in a new tab)
- git.kernel.org/stable/c/fa0b9b2b7ae3539908d69c2b9ac0d144d9bc5139 (opens in a new tab)
- access.redhat.com/security/cve/CVE-2026-52923 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2492094 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-52923.json (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:61692 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:63189 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:52764 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:53330 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:51603 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:48386 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:49031 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:49212 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:49857 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:47248 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:52649 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:49851 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:51604 (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-784472.html (opens in a new tab)