---
id: MAL-2026-16264
title: Malicious code in aiosendletter (PyPI)
summary: Malicious code in aiosendletter (PyPI)
severity: critical
exploited: true
vendor: aiosendletter
product: aiosendletter
ecosystem: pip
affected:
  - aiosendletter
published: '2026-09-17'
updated: '2026-09-22'
sourceUpdated: '2026-09-22T23:30:07.052853488Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/MAL-2026-16264'
references:
  - url: 'https://bad-packages.kam193.eu/pypi/package/aiosendletter'
  - url: 'https://pypi.org/project/aiosendletter/4.3/'
  - url: 'https://pypi.org/project/aiosendletter/4.6/'
  - url: 'https://pypi.org/project/aiosendletter/3.8/'
  - url: 'https://pypi.org/project/aiosendletter/4.5/'
  - url: 'https://pypi.org/project/aiosendletter/3.9/'
  - url: 'https://pypi.org/project/aiosendletter/0.2.0/'
  - url: 'https://pypi.org/project/aiosendletter/3.7/'
  - url: 'https://pypi.org/project/aiosendletter/4.1/'
  - url: 'https://pypi.org/project/aiosendletter/4.0/'
tags:
  - osv
  - pip
  - malware
ingestedAt: '2026-09-18T16:21:29.478Z'
---

## Overview


---
_-= Per source details. Do not edit below this line.=-_

## Source: amazon-inspector (29baa6f2cbfb2ef9907be7830505e33e82b5a1e6a45eb7f995022d09f5841f09)
The package advertises itself as a 'safe bug reporter' but its init() function archives the contents of %LOCALAPPDATA%\logs with shutil.make_archive and POSTs the resulting archive to a hardcoded, non-configurable Cloudflare Workers endpoint at https://sparkling-pine-f202.stilluer-sweden.workers.dev/. The destination is author-controlled, the caller has no way to redirect or disable it, and code comments indicate the target directory is expected to include a Telegram bot token folder — the collected data is credential-adjacent local state leaving the installer's machine. On Windows the same function calls ctypes.windll.shell32.ShellExecuteW with the 'runas' verb to relaunch the interpreter under UAC elevation before performing the archive-and-upload, broadening the set of files reachable for collection. Separately, pyproject.toml declares 'ctypes' as a runtime dependency; ctypes is a Python standard-library module, so pip resolves this name against PyPI and installs whatever package is published there under 'ctypes', executing that third party's code at install time. The cover-story description, the hardcoded off-host destination for locally-collected data, the privilege escalation, and the stdlib-name dependency-confusion vector jointly constitute an active supply-chain attack on installers.

## Source: kam193 (4e81e3b63bbe719f6d0bdd42930bb2f3235b8e41cbacf449743bb7dca67c9f08)
Package hides code to exfiltrate files. Most releases target unclear files, but some reveal the goal to exfiltrate sensitive Telegram data.


---

Category: MALICIOUS - The campaign has clearly malicious intent, like infostealers.


Campaign: 2026-09-aiosendletter


Reasons (based on the campaign):


 - files-exfiltration


 - target:telegram


## Affected packages

- `aiosendletter`

## Remediation

Refer to the advisory for the patched release.