---
id: CVE-2019-11340
aliases:
  - GHSA-q9h8-gpw5-c95c
  - PYSEC-2026-843
title: Matrix Sydent mishandles emails
summary: Matrix Sydent mishandles emails
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N'
vendor: matrix-sydent
product: matrix-sydent
ecosystem: pip
affected:
  - matrix-sydent < 1.0.2
patched:
  - matrix-sydent 1.0.2
published: '2022-05-24'
updated: '2026-07-07'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-q9h8-gpw5-c95c'
references:
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2019-11340'
  - url: >-
      https://github.com/matrix-org/sydent/commit/4e1cfff53429c49c87d5c457a18ed435520044fc
  - url: 'https://github.com/matrix-org/sydent/compare/7c002cd...09278fb'
  - url: 'https://matrix.org/blog/2019/04/18/security-update-sydent-1-0-2'
  - url: 'https://twitter.com/matrixdotorg/status/1118934335963500545'
tags:
  - osv
  - pip
epss: 0.01876
epssPercentile: 0.78486
ingestedAt: '2026-07-08T18:25:52.378Z'
---

## Overview

util/emailutils.py in Matrix Sydent before 1.0.2 mishandles registration restrictions that are based on e-mail domain, if the allowed_local_3pids option is enabled. This occurs because of potentially unwanted behavior in Python, in which an email.utils.parseaddr call on user@bad.example.net@good.example.com returns the user@bad.example.net substring.

## Affected packages

- `matrix-sydent < 1.0.2`

## Remediation

Upgrade to a patched release:

- `matrix-sydent 1.0.2`