Inefficient Regular Expression Complexity Affecting localstack package, versions <4.14.0-r4


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

Social Trends
EPSS
0.72% (50th percentile)

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  • Snyk IDSNYK-CHAINGUARDLATEST-LOCALSTACK-15753836
  • published23 Mar 2026
  • disclosed12 Mar 2026

Introduced: 12 Mar 2026

CVE-2026-28356  (opens in a new tab)
CWE-1333  (opens in a new tab)

How to fix?

Upgrade Chainguard localstack to version 4.14.0-r4 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream localstack package and not the localstack package as distributed by Chainguard. See How to fix? for Chainguard relevant fixed versions and status.

multipart is a fast multipart/form-data parser for python. Prior to 1.2.2, 1.3.1 and 1.4.0-dev, the parse_options_header() function in multipart.py uses a regular expression with an ambiguous alternation, which can cause exponential backtracking (ReDoS) when parsing maliciously crafted HTTP or multipart segment headers. This can be abused for denial of service (DoS) attacks against web applications using this library to parse request headers or multipart/form-data streams. The issue is fixed in 1.2.2, 1.3.1 and 1.4.0-dev.

CVSS Base Scores

version 3.1