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Review reviewHigh

CVE-2021-47505

Linux Linux, linux kernel

In the Linux kernel, the following vulnerability has been resolved: aio: fix use-after-free due to missing POLLFREE handling signalfd_poll() and binder_poll() are special in that they use a waitqueue whose lifetime is the current task, rather than the struct file as is normally the case. This is okay for blocking polls, since a blocking poll occurs within one task; however, non-blocking polls require another solution. This solution is for the queue to be cleared before it is freed, by sending a POLLFREE notification to all waiters. Unfortunately, only eventpoll handles POLLFREE. A second ty...

CVSS
7.8
EPSS
0.25%
16.6% percentile
CISA KEV
Not listed
Published
2024.05.25
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability0.25%
Technical severityCVSS 7.8

Vulnerability overview

In the Linux kernel, the following vulnerability has been resolved: aio: fix use-after-free due to missing POLLFREE handling signalfd_poll() and binder_poll() are special in that they use a waitqueue whose lifetime is the current task, rather than the struct file as is normally the case. This is okay for blocking polls, since a blocking poll occurs within one task; however, non-blocking polls require another solution. This solution is for the queue to be cleared before it is freed, by sending a POLLFREE notification to all waiters. Unfortunately, only eventpoll handles POLLFREE. A second ty...

Affected product and versions

Product
Linux Linux, linux kernel
Affected versions
>= 2c14fa838cbefc23cf1c73ca167ed85b274b2913 < 321fba81ec034f88aea4898993c1bf15605c023f, >= 2c14fa838cbefc23cf1c73ca167ed85b274b2913 < 4105e6a128e8a98455dfc9e6dbb2ab0c33c4497f, >= 2c14fa838cbefc23cf1c73ca167ed85b274b2913 < 47ffefd88abfffe8a040bcc1dd0554d4ea6f7689, >= 2c14fa838cbefc23cf1c73ca167ed85b274b2913 < 60d311f9e6381d779d7d53371f87285698ecee24, >= 2c14fa838cbefc23cf1c73ca167ed85b274b2913 < 50252e4b5e989ce64555c7aef7516bdefc2fea72, >= 4.18, >= 4.18 < 4.19.221, >= 4.20 < 5.4.165, >= 5.5 < 5.10.85, >= 5.11 < 5.15.8, 5.16
Fixed versions
4.19.221, 5.4.165, 5.10.85, 5.15.8

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux Linux, linux kernel and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE
CWE-416
CVE-2021-47505 — Linux Linux, linux kernel | SECUFOCUS NOW