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CVE-2021-47556

16
FAUCET Score

CVE-2021-47556 is a NULL pointer dereference vulnerability in the Linux kernel's ethtool_set_coalesce() function, affecting the legacy ioctl path. This flaw occurs when a network driver provides only one of the .get_coalesce() or .set_coalesce() callbacks, leading to a system crash instead of an error. With a CVSS score of 5.5 (Medium), it requires local access and low privileges to trigger, resulting in a denial of service (system crash). There is no evidence of active exploitation, public exploit code, or significant community discussion, and it is not listed in CISA's KEV catalog.

Impacted Technologies

VendorProductVersion(s)CPE
>= 5.15, < 5.15.6CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.5MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
1.8
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.18%
Probability of exploitation in next 30 days
EPSS Percentile
8.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0018 is in the 42nd percentile among its peer group of 15,940 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (4)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: kernel-rt-0:4.18.0-372.9.1.rt7.166.el8
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: kernel-0:4.18.0-372.9.1.el8
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 9Fixed in: kernel-0:5.14.0-162.6.1.el9_1
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 9Fixed in: kernel-rt-0:5.14.0-162.6.1.rt21.168.el9_1
View patch

Vendor Advisories (1)

redhatCVE-2021-47556Moderate

kernel: ethtool: ioctl: fix potential NULL deref in ethtool_set_coalesce()

May 24, 2024

References

git.kernel.org / stable/c/0276af2176c78771da7f311621a25d7608045827
Patch
git.kernel.org / stable/c/abfdd9e2f0f9699015d72317f74154d3e53664e6
Patch