CVE-2026-63799

Kernel memory corruption via sentinel bit clear

Published Jul 19, 2026 · Updated Jul 19, 2026

Out-of-bounds memory access in Linux Kernel 6.19 through 7.1.2 allows local users to corrupt unpredictable kernel memory. The mm_cid_fixup_cpus_to_tasks() path marks MM_CID_UNSET as in transit, and mm_cid_schedout() later passes that sentinel to clear_bit() as a bitmap index. Triggering requires per-CPU CID mode, a fork or exec window before CID assignment, and a per-task fixup; the result is fixed-offset, single-bit corruption rather than an attacker-chosen write.

CVSS severity7.8
High
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds memory access in Linux Kernel 6.19 through 7.1.2 allows local users to corrupt unpredictable kernel memory. The mm_cid_fixup_cpus_to_tasks() path marks MM_CID_UNSET as in transit, and mm_cid_schedout() later passes that sentinel to clear_bit() as a bitmap index. Triggering requires per-CPU CID mode, a fork or exec window before CID assignment, and a per-task fixup; the result is fixed-offset, single-bit corruption rather than an attacker-chosen write.

The record

CVE
CVE-2026-63799
Published
Jul 19, 2026
Updated
Jul 19, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-125, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.19
  2. Affected versionversion=fbd0e71dc370af73f6b316e4de9eed273dd90340 <8d32856fb72ba976d9c87ba405fd17e80419934c
  3. Affected versionversion=fbd0e71dc370af73f6b316e4de9eed273dd90340 <de3ab9bd3133899efb92e4cd05ba4203e58fc0a3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.19; version=fbd0e71dc370af73f6b316e4de9eed273dd90340 <8d32856fb72ba976d9c87ba405fd17e80419934c; version=fbd0e71dc370af73f6b316e4de9eed273dd90340 <de3ab9bd3133899efb92e4cd05ba4203e58fc0a3

Published CVSS scores

7.8kernel.orgCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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