SB2026111219 - Inefficient Algorithmic Complexity in CBOR2

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Main Vulnerability Database SB2026111219

SB2026111219 - Inefficient Algorithmic Complexity in CBOR2

Published: November 12, 2026

Security Bulletin ID SB2026111219
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Remote access
Highest impact Partial DoS

Breakdown by Severity

Medium 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Inefficient Algorithmic Complexity (CVE-ID: N/A)

CWE-ID: CWE-407 - Inefficient Algorithmic Complexity

CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]


The vulnerability allows a remote attacker to cause a denial of service through excessive CPU consumption in applications decoding untrusted CBOR.

The vulnerability exists due to inefficient algorithmic complexity in cbor2's decode_bytestring() and decode_string() functions when decoding indefinite-length strings with allow_indefinite=True, as repeated concatenation copies accumulated immutable data. A remote attacker can submit valid CBOR byte or text strings containing many tiny chunks to trigger quadratic copying and degrade application availability.


Remediation

Install update from vendor's website.

References