Out-of-bounds read in Linux kernel dm ioctl leaks adjacent memory
Key facts
- Attack vector
- —
- Privileges required
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- User interaction
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- Attack complexity
- —
- Impact type
- —
- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 7 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
The Linux kernel from 2.6.25 is affected. The device mapper ioctl code sets the data start offset without checking the caller's buffer size, so it can run past the end of the allocation. Only root can trigger this out-of-bounds read, which can copy adjacent kernel memory back to userspace.
Written with Claude Haiku 5.5 from the sources below · 2026-11-07
Description from the CNA
In the Linux kernel, the following vulnerability has been resolved: dm ioctl: don't let data_start run past the buffer struct dm_ioctl has seven bytes of trailing padding, so the smallest buffer userspace is allowed to ask for, offsetof(struct dm_ioctl, data), is seven bytes shorter than sizeof(struct dm_ioctl). get_result_buffer() sets data_start to sizeof(struct dm_ioctl) without looking at how big the buffer actually is. Ask for the minimum and data_start ends up seven bytes past the end. Callers add it to data_size, and ctl_ioctl() copies that much back to userspace: BUG: KASAN: slab-out-of-bounds in _copy_to_user+0xad/0xd0 Read of size 312 at addr ffff8880169e4c00 by task repro-dm/140 ctl_ioctl+0x5e3/0xcb0 dm_ctl_ioctl+0x25/0x40 allocated 305-byte region [ffff8880169e4c00, ffff8880169e4d31) A DM_LIST_DEVICES with data_size set to 305 is enough to hit it, and the seven bytes that leak are whatever sat next to the allocation. Clamp data_start to the buffer size. Note that this is not a security bug because the out-of-bounds read can only be triggered by root.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 2.6.25 and later | 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.113, 6.18.57, 7.2.11, 7.3 | Patch available | CNA |
- Linux VendorLinux Affected 2.6.25 and later Fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.113, 6.18.57, 7.2.11, 7.3 Patch available CNA
Remediation
Update the Linux kernel to 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.113, 6.18.57, 7.2.11 or 7.3. Red Hat lists no fix planned for Red Hat Enterprise Linux 6 and no fix available for Red Hat Enterprise Linux 7, 8, 9, 10, OpenShift Container Platform 4 and OpenShift Container Platform 5.
Written with Claude Haiku 5.5 from the sources below · 2026-11-07
- Fix · CNA Linux (Linux) Fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.113, 6.18.57, 7.2.11, 7.3
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-23 Threatist record created from CVE-2026-99063
- 2026-10-23 Alias added: GHSA-vqpj-f54g-hrc3
- 2026-10-27 Affected versions changed · Red Hat
- 2026-10-27 CVSS score added · Red Hat
- 2026-10-30 Fix available: Linux/[email protected], Linux/[email protected], Linux/[email protected] +3 · CNA
- 2026-10-30 3 new references · CNA
- 2026-11-07 Affected versions changed · Red Hat
References
Other 8
- https://git.kernel.org/stable/c/aaa93e41ae308ad9ff9d9ba3296a0d0f4d45bad3
- https://git.kernel.org/stable/c/f171054f3c4cfc4dc0cb622ec5b15793e5f23029
- https://git.kernel.org/stable/c/afe80ec31464f4c54cc1bc658753bc14cb14bd6c
- https://git.kernel.org/stable/c/98195e822343a656b92e235847ab3e72b1a3f920
- https://git.kernel.org/stable/c/e5c3f3d8935ecc64c962fb66e6a86dbf79218f61
- https://git.kernel.org/stable/c/5680b6fb3054677d4ee65d3baba24b649f1b430e
- https://git.kernel.org/stable/c/725b49c689bbb29ef740b0d6b5ea9390baa9a695
- https://git.kernel.org/stable/c/9b3fcf519d370df94a56f3b272d9eddffffa5be8
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Sources
- CVE-2026-99063 · CVE Program
- CVE-2026-99063 · NVD
- FIRST EPSS
- GHSA-vqpj-f54g-hrc3 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-99063 · Red Hat security data · CC BY 4.0
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