VulnerabilityPublished 23 Oct 2026

CVE-2026-99063: Linux kernel · dm ioctl: don't let data_start run past the buffer

Source GCVE Database

Authoritative record:CVE-2026-99063· Low

Not known to be exploited · fixed in e5c3f3d8935ecc64c962fb66e6a86dbf79218f61 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 17:16 UTC

Severity

Low

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in e5c3f3d8935ecc64c962fb66e6a86dbf79218f61, 98195e822343a656b92e235847ab3e72b1a3f920, 5680b6fb3054677d4ee65d3baba24b649f1b430e +2

Exploitation evidence

Disclosed: evidence found.
CVE published 23 Oct 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.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-vqpj-f54g-hrc3

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 76c072b48e39e9291fbf02d6c912cf27d65e093d, < e5c3f3d8935ecc64c962fb66e6a86dbf79218f61	Fixed in e5c3f3d8935ecc64c962fb66e6a86dbf79218f61
LinuxLinux	Affected ≥ 76c072b48e39e9291fbf02d6c912cf27d65e093d, < 98195e822343a656b92e235847ab3e72b1a3f920	Fixed in 98195e822343a656b92e235847ab3e72b1a3f920
LinuxLinux	Affected ≥ 76c072b48e39e9291fbf02d6c912cf27d65e093d, < 5680b6fb3054677d4ee65d3baba24b649f1b430e	Fixed in 5680b6fb3054677d4ee65d3baba24b649f1b430e
LinuxLinux	Affected ≥ 76c072b48e39e9291fbf02d6c912cf27d65e093d, < 725b49c689bbb29ef740b0d6b5ea9390baa9a695	Fixed in 725b49c689bbb29ef740b0d6b5ea9390baa9a695
LinuxLinux	Affected ≥ 76c072b48e39e9291fbf02d6c912cf27d65e093d, < 9b3fcf519d370df94a56f3b272d9eddffffa5be8	Fixed in 9b3fcf519d370df94a56f3b272d9eddffffa5be8
LinuxLinux	Affected =2.6.25	Fixed in–

Description

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.

References

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