Enterprise LinuxOperating system · Redhat
CVE-2021-3543
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA flaw null pointer dereference in the Nitro Enclaves kernel driver was found in the way that Enclaves VMs forces closures on the enclave file descriptor. A local user of a host machine could use this flaw to crash the system or escalate their privileges on the system.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceA null pointer dereference vulnerability exists in the Nitro Enclaves kernel driver where improper handling of enclave VM closure operations on the enclave file descriptor allows a local attacker to trigger a kernel panic or achieve local privilege escalation to root.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Enterprise LinuxOperating system
= 8.0
FedoraOperating system
= 34< 5.10.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Verify if Nitro Enclaves kernel driver is presentCheck for the nitro_enclaves kernel module by running 'lsmod | grep nitro_enclaves' or attempting to load it with 'modprobe nitro_enclaves'Affected if The module loads successfully or is found loaded, indicating the Nitro Enclaves driver is available on the system
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Check installed kernel versionRun 'uname -r' to get the running kernel version and compare it against the upstream fix version 5.10.0Affected if The kernel version is earlier than 5.10.0 and the Nitro Enclaves driver is present
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Confirm OS version matches affected distributionsRun 'cat /etc/redhat-release' for RHEL systems or 'cat /etc/fedora-release' for Fedora systems to identify the exact OS versionAffected if The system is Red Hat Enterprise Linux 8.0 or Fedora 34, and the Nitro Enclaves driver is loaded or loadable
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Check for Nitro Enclaves user toolingLook for the 'nitro-cli' command or related enclave management tools by running 'which nitro-cli' or 'rpm -qa | grep nitro'Affected if Nitro Enclaves user-space tools are installed, indicating the feature is in use
The system is affected if Nitro Enclaves driver is present and the kernel/OS version matches RHEL 8.0, Fedora 34, or a kernel version earlier than 5.10.0.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor data5.10.0
Apply the upstream kernel patch for CVE-2021-3543, which addresses the null pointer dereference in the Nitro Enclaves driver. Ensure systems are updated to a kernel version containing the fix, and restrict local user access to untrusted accounts until patching is complete.
Fix this in Enterprise Linux
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,888.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-3543 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-3543 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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