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TI-2021-22142 Aliases CVE-2021-47491GHSA-8g2p-p68f-4wqr

mm: khugepaged: skip huge page collapse for special files

Priority LOW 24Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · None · High
Fix status
Partial Red Hat: 4 fixed, 2 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.

Summary

In the Linux kernel, the following vulnerability has been resolved: mm: khugepaged: skip huge page collapse for special files The read-only THP for filesystems will collapse THP for files opened readonly and mapped with VM_EXEC. The intended usecase is to avoid TLB misses for large text segments. But it doesn't restrict the file types so a THP could be collapsed for a non-regular file, for example, block device, if it is opened readonly and mapped with EXEC permission. This may cause bugs, like [1] and [2]. This is definitely not the intended usecase, so just collapse THP for regular files in order to close the attack surface. [[email protected]: fix vm_file check [3]]

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0021 11th percentileScored 2026-11-07
Fix Partial Linux (Linux): 5.10.78, 5.14.16, 5.15Red Hat: 2 advisoriesRed Hat: 4 fixed, 2 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux5.4 and later5.10.78, 5.14.16, 5.15Patch availableCNA
  • Linux VendorLinux Affected 5.4 and later Fixed in 5.10.78, 5.14.16, 5.15 Patch available CNA

CPE configurations NVD · 8

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*5.4 to before 5.10.78; 5.11 to before 5.14.16VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.15:rc1:*:*:*:*:*:*5.15 rc1VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.15:rc2:*:*:*:*:*:*5.15 rc2VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.15:rc3:*:*:*:*:*:*5.15 rc3VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.15:rc4:*:*:*:*:*:*5.15 rc4VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.15:rc5:*:*:*:*:*:*5.15 rc5VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.15:rc6:*:*:*:*:*:*5.15 rc6VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.15:rc7:*:*:*:*:*:*5.15 rc7VulnerableLinux
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 5.4 to before 5.10.78; 5.11 to before 5.14.16 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.15:rc1:*:*:*:*:*:* Versions 5.15 rc1 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.15:rc2:*:*:*:*:*:* Versions 5.15 rc2 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.15:rc3:*:*:*:*:*:* Versions 5.15 rc3 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.15:rc4:*:*:*:*:*:* Versions 5.15 rc4 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.15:rc5:*:*:*:*:*:* Versions 5.15 rc5 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.15:rc6:*:*:*:*:*:* Versions 5.15 rc6 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.15:rc7:*:*:*:*:*:* Versions 5.15 rc7 Vulnerable ·Linux

Remediation

  • Fix · CNA Linux (Linux) Fixed in 5.10.78, 5.14.16, 5.15

Red Hat 2 advisories

  • RHSA-2024:5101 Released 2024-08-08 · Red Hat rating Important
    kernel security update
    • Red Hat Enterprise Linux BaseOS (v. 8) bpftool-4.18.0-553.16.1.el8_10, kernel-4.18.0-553.16.1.el8_10, kernel-abi-stablelists-4.18.0-553.16.1.el8_10 +19
    • Red Hat Enterprise Linux CRB (v. 8) kernel-tools-libs-devel-4.18.0-553.16.1.el8_10
  • RHSA-2024:5102 Released 2024-08-08 · Red Hat rating Important
    kernel-rt security update
    • Red Hat Enterprise Linux NFV (v. 8) kernel-rt-4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-core-4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-debug-4.18.0-553.16.1.rt7.357.el8_10 +9
    • Red Hat Enterprise Linux RT (v. 8) kernel-rt-4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-core-4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-debug-4.18.0-553.16.1.rt7.357.el8_10 +7

Vendor assessments

Red Hat

Red Hat rating: Low. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux 7AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux BaseOS (v. 8)Fixed RHSA-2024:5101
Red Hat Enterprise Linux CRB (v. 8)Fixed RHSA-2024:5101
Red Hat Enterprise Linux NFV (v. 8)Fixed RHSA-2024:5102
Red Hat Enterprise Linux RT (v. 8)Fixed RHSA-2024:5102
Not affected: 1 product
  • Red Hat Enterprise Linux 9

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-47491
  2. 2026-10-03 Alias added: GHSA-8g2p-p68f-4wqr

References

Patch 3

  • TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
  • TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
  • TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
  • TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
  • TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
See all 15278 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences