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Debian LinuxOperating system · Debian

CVE-2023-39949

HIGH · 7.5 CVSS v3.1 Published 2023-08-11
Fix available
A fix is available. Upgrade to 2.6.5 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges 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
eprosima Fast DDS is a C++ implementation of the Data Distribution Service standard of the Object Management Group. Prior to versions 2.9.1 and 2.6.5, improper validation of sequence numbers may lead to remotely reachable assertion failure. This can remotely crash any Fast-DDS process. Versions 2.9.1 and 2.6.5 contain a patch for this issue.

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 · high confidence

eprosima Fast DDS versions prior to 2.9.1 and 2.6.5 contain improper validation of sequence numbers in the DDS protocol implementation, allowing remote attackers to trigger an assertion failure by sending specially crafted packets with invalid sequence numbers, resulting in denial-of-service via process crash.

MitigationUpgrade Fast DDS to version 2.9.1 or 2.6.5 (depending on the used release branch) to obtain the patched library with proper sequence number validation.

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
Debian LinuxOperating system
Affected:= 11.0= 12.0
Fast DdsApplication
Affected:>= 2.6.0, < 2.6.5= 2.9.0

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/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. Identify if Fast DDS is installed
    Search for installed Fast DDS libraries or packages on the system. On Debian-based systems, run: dpkg -l | grep -i fast-dds or apt list --installed 2>/dev/null | grep -i fast-dds. On Linux systems, also check for libfastrtps.so files: find /usr -name "libfastrtps*" 2>/dev/null
    Affected if Fast DDS library is present on the system
  2. Determine the installed Fast DDS version
    If a package is installed, query its version. On Debian: dpkg -l <package-name> or apt show <package-name>. If a library file is found, check any version metadata in the filename or associated metadata files
    Affected if The version cannot be determined or the package is not found (uncertain status)
  3. Compare version against vulnerable ranges
    Check if the installed version falls into: 2.6.0 through 2.6.4 (any version >=2.6.0 but <2.6.5), or exactly version 2.9.0. These are the vulnerable versions per the CVE
    Affected if Installed version is 2.6.0, 2.6.1, 2.6.2, 2.6.3, 2.6.4, or 2.9.0, indicating the vulnerability is present
  4. Check if Fast DDS is in use
    Review application dependencies or configurations that load Fast DDS (libfastrtps). Check application logs, configuration files, or running processes that reference Fast DDS or RTPS protocol usage
    Affected if Applications depend on a vulnerable Fast DDS version and process RTPS network traffic

The environment is affected if a Fast DDS installation with version 2.6.0-2.6.4 or 2.9.0 is present and actively processing RTPS network traffic.

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.

dbcve · scoped
Upgrade available Upgrade to 2.6.5 or later
Fixed in 2.6.5
Interim mitigation

Upgrade Fast DDS to version 2.9.1 or 2.6.5 (depending on the used release branch) to obtain the patched library with proper sequence number validation.

Recommended fix High confidence

Fast DDS 2.9.1 (or 2.6.5 for the 2.6.x branch)

  1. 1. Identify the currently installed Fast DDS version using package manager or project dependency file
  2. 2. If using Fast DDS 2.9.0, upgrade to version 2.9.1
  3. 3. If using Fast DDS between 2.6.0 and 2.6.4, upgrade to version 2.6.5
  4. 4. For Debian systems, ensure security updates are applied: run 'apt update && apt upgrade' for Debian 11 or 12
  5. 5. Rebuild any applications that link against Fast DDS libraries after upgrading
  6. 6. Verify the upgrade was successful by checking the new version

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Debian Linux Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
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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-2023-39949 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