CVE-2021-33033
HIGHCVSS 7.8/10EPSS 0.57%
Last modified
CVE-2021-33033 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. 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.. EPSS estimates a 0.57% chance of exploitation in the next 30 days.
Description
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.
Metrics
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Linux | Linux Kernel | >= 2.6.28, < 4.9.298 |
| Linux | Linux Kernel | >= 4.10, < 4.14.226 |
| Linux | Linux Kernel | >= 4.15, < 4.19.181 |
| Linux | Linux Kernel | >= 4.20, < 5.4.106 |
| Linux | Linux Kernel | >= 5.5, < 5.10.24 |
| Linux | Linux Kernel | >= 5.11, < 5.11.7 |
References
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.14Mailing List, Patch, Vendor Advisory
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.7Mailing List, Patch, Vendor Advisory
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1165affd484889d4986cf3b724318935a0b120d8Mailing List, Patch, Vendor Advisory
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ad5d07f4a9cd671233ae20983848874731102c08Mailing List, Patch, Vendor Advisory
- https://sites.google.com/view/syzscope/kasan-use-after-free-read-in-cipso_v4_genoptExploit, Third Party Advisory
- https://syzkaller.appspot.com/bug?id=96e7d345748d8814901c91cd92084ed04b46701eExploit, Mailing List, Third Party Advisory
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.14Mailing List, Patch, Vendor Advisory
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.7Mailing List, Patch, Vendor Advisory
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1165affd484889d4986cf3b724318935a0b120d8Mailing List, Patch, Vendor Advisory
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ad5d07f4a9cd671233ae20983848874731102c08Mailing List, Patch, Vendor Advisory
- https://sites.google.com/view/syzscope/kasan-use-after-free-read-in-cipso_v4_genoptExploit, Third Party Advisory
- https://syzkaller.appspot.com/bug?id=96e7d345748d8814901c91cd92084ed04b46701eExploit, Mailing List, Third Party Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2021-33033?
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.
How severe is CVE-2021-33033?
CVE-2021-33033 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.57% probability of exploitation in the next 30 days.
How do I fix CVE-2021-33033?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
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Are you affected by CVE-2021-33033?
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Scan your code nowSource: NVD / NIST