CyberSecBulletin
CVE-2023-39946NVD status: Modified

Fast-DDS: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2023-39946 is a high-severity out-of-bounds write vulnerability in Fast-DDS from eProsima, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Fast-DDS versions: < 2.6.6; >= 2.7.0, < 2.9.2; >= 2.10.0, < 2.10.2, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.89% chance of exploitation within 30 days, higher than 60% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of Fast-DDS you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on github.com for workarounds and exact fixed builds.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
eProsimaFast-DDS< 2.6.6; >= 2.7.0, < 2.9.2; >= 2.10.0, < 2.10.2; = 2.11.0Not stated
DebianDebian Linux11.0; 12.0Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.18.2HighCNA (github.com)
CVSS 3.17.5HighNVD

Official description

eprosima Fast DDS is a C++ implementation of the Data Distribution Service standard of the Object Management Group. Prior to versions 2.11.1, 2.10.2, 2.9.2, and 2.6.6, heap can be overflowed by providing a PID_PROPERTY_LIST parameter that contains a CDR string with length larger than the size of actual content. In `eprosima::fastdds::dds::ParameterPropertyList_t::push_back_helper`, `memcpy` is called to first copy the octet'ized length and then to copy the data into `properties_.data`. At the second memcpy, both `data` and `size` can be controlled by anyone that sends the CDR string to the discovery multicast port. This can remotely crash any Fast-DDS process. Versions 2.11.1, 2.10.2, 2.9.2, and 2.6.6 contain a patch for this issue.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Out-of-bounds Write

The product writes data past the end, or before the beginning, of the intended buffer.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.

More Out-of-bounds Write vulnerabilities (CWE-787)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Other vulnerabilities in Fast-DDS

All Fast-DDS vulnerabilities

Recent Out-of-bounds Write vulnerabilities

Spotted an error? Tell us.