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LinuxOperating system · Oracle

CVE-2026-21996

MEDIUM · 5.5 CVSS v3.1 Published 2026-05-01
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
57/100
Remediation priority · Elevated
Zero-click

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 · unedited
An unprivileged attacker can reliably trigger a crash of the dtrace process with a malicious ELF binary due to an integer Divide-by-Zero in Pbuild_file_symtab()

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 confidence

A divide-by-zero vulnerability exists in the dtrace utility's Pbuild_file_symtab() function when parsing ELF binaries. An unprivileged attacker can trigger this by providing a maliciously crafted ELF file, causing the dtrace process to crash.

MitigationImplement input validation in Pbuild_file_symtab() to verify ELF structure integrity and prevent division-by-zero conditions before processing symbol tables. Consider adding ELF header validation and bounds checking.

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
Affected:= 8= 9= 10

CVSS 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 checks

Work through these to decide whether this CVE applies to you.

  1. Check if dtrace utility is installed
    Run 'which dtrace' or 'command -v dtrace' to verify the dtrace binary exists on the system
    Affected if dtrace command is found and executable
  2. Identify Oracle Linux version
    Run 'cat /etc/oracle-release' or 'cat /etc/redhat-release' to determine the installed Oracle Linux major version
    Affected if Version is 8, 9, or 10 (matching the affected version range)
  3. Verify dtrace can process ELF binaries
    Run 'dtrace -l' or attempt to trace a process to confirm dtrace functionality is operational
    Affected if dtrace executes without errors and can access its tracing features
  4. Check if unprivileged users can invoke dtrace
    Review dtrace permissions using 'ls -la $(which dtrace)' and check if any kernel dtrace policies restrict usage to root only
    Affected if dtrace can be invoked by the user checking for vulnerability, or permissions allow non-root execution

If running Oracle Linux version 8, 9, or 10 with dtrace installed and executable, the environment is potentially affected by this divide-by-zero vulnerability when processing malicious ELF files.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Implement input validation in Pbuild_file_symtab() to verify ELF structure integrity and prevent division-by-zero conditions before processing symbol tables. Consider adding ELF header validation and bounds checking.

Fix this in Linux Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-21996 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data