LinuxOperating system · Oracle
CVE-2026-21991
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 DTrace component, dtprobed, allows arbitrary file creation through crafted USDT provider names.
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 confidenceThe dtprobed component of DTrace (dynamic tracing framework) fails to properly validate or sanitize USDT (User Statically Defined Tracing) provider names, allowing an attacker to create arbitrary files on the system with the privileges of the dtprobed process. This file creation vulnerability stems from the component using attacker-controlled input from provider names directly in file path operations without adequate path sanitization.
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
LinuxOperating system
= 8= 9= 10CVSS 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
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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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Check if DTrace dtprobed is installedRun 'rpm -qa | grep -i dtrace' or 'rpm -q dtrace-utils' on Oracle Linux to list installed DTrace packagesAffected if Any DTrace package is installed (the dtprobed component is present)
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Verify dtprobed process is runningRun 'ps aux | grep dtprobed' to check if the dtprobed daemon is currently activeAffected if The dtprobed process is running and accessible to the user
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Determine DTrace package versionRun 'rpm -q --qf "%{VERSION}-%{RELEASE}" dtrace-utils' or check Oracle Linux yum history for DTrace package installation detailsAffected if The installed version matches Oracle Linux 8, 9, or 10 (exact versions)
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Check if USDT provider functionality is accessibleReview application configurations and running processes for USDT (User Statically Defined Tracing) probe definitions; check /proc/*/usdt for active USDT providers if availableAffected if USDT provider names can be created or modified by an attacker (user has ability to define USDT providers)
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Assess dtprobed binary permissions and accessRun 'ls -la /usr/sbin/dtprobed' (or locate dtprobed binary) and verify which users/groups can execute or interact with itAffected if Untrusted users have access to execute dtprobed or define USDT provider names
A user is affected if DTrace/dtprobed is installed on Oracle Linux 8, 9, or 10, the dtprobed process is running, and untrusted users can define or control USDT provider names that get used by dtprobed.
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 dataRestrict access to the dtprobed component and DTrace functionality to trusted users only. Monitor for unusual file creation activity in system directories. Apply vendor patches when available to address the input validation flaw in USDT provider name handling.
Fix this in Linux
Scoped from the published advisory
- Consultation4.0 h
- Implementation12.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $7,808.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-21991 — 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-2026-21991 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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