ReviewHigh

CVE-2021-33033

linux kernel

The Linux kernel before 5.11.14 has a use-after-free in cipso_v4_genopt in net/ipv4/cipso_ipv4.c because the CIPSO and CALIPSO refcounting for the DOI definitions is mishandled, aka CID-ad5d07f4a9cd. This leads to writing an arbitrary value.

CVSS
7.8
EPSS
0.57%
44.8% percentile
CISA KEV
Not listed
Published
2021.05.15
PRIORITY ASSESSMENT

Review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability0.57%
Technical severityCVSS 7.8

Vulnerability overview

The Linux kernel before 5.11.14 has a use-after-free in cipso_v4_genopt in net/ipv4/cipso_ipv4.c because the CIPSO and CALIPSO refcounting for the DOI definitions is mishandled, aka CID-ad5d07f4a9cd. This leads to writing an arbitrary value.

Affected product and versions

Product
linux kernel
Affected versions
>= 2.6.28 < 4.9.298, >= 4.10 < 4.14.226, >= 4.15 < 4.19.181, >= 4.20 < 5.4.106, >= 5.5 < 5.10.24, >= 5.11 < 5.11.7
Fixed versions
4.9.298, 4.14.226, 4.19.181, 5.4.106, 5.10.24, 5.11.7

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that 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