CVE-2020-26243 : Security Advisory and Response

Nanopb is a small code-size Protocol Buffers implementation vulnerable to memory leaks in versions prior to 0.4.4 and 0.3.9.7. This CVE-2020-26243 impacts systems using Nanopb with specific decoding scenarios.

Understanding CVE-2020-26243

Nanopb vulnerability leading to memory leaks.

What is CVE-2020-26243?

Nanopb versions before 0.4.4 and 0.3.9.7 can leak memory during decoding under certain conditions, potentially affecting systems with dynamic allocation enabled.

The Impact of CVE-2020-26243

CVSS Score: 7.5 (High)
Attack Vector: Network
Availability Impact: High
No Confidentiality or Integrity Impact
No Privileges Required
Scope: Unchanged
No User Interaction Required

Technical Details of CVE-2020-26243

Nanopb vulnerability specifics.

Vulnerability Description

Decoding specific messages in Nanopb can lead to memory leaks due to improper handling of dynamic fields within static submessages.

Affected Systems and Versions

Affected Versions: < 0.3.9.7, >= 0.4.0, < 0.4.4

Exploitation Mechanism

The vulnerability arises when decoding messages with static submessages containing dynamic fields multiple times.

Mitigation and Prevention

Protecting systems from CVE-2020-26243.

Immediate Steps to Take

Apply patches or updates to Nanopb versions 0.3.9.7 and 0.4.4.
Implement workarounds like setting

no_unions

for the oneof field or using

FT_POINTER

for submessage fields.

Long-Term Security Practices

Regularly update Nanopb to the latest secure versions.
Employ an arena allocator for Nanopb to ensure proper memory management.

Patching and Updates

Refer to official Nanopb sources for patch releases and changelogs.