---
id: "MAL-2026-16264"
kind: "package"
aliases: ["MAL-2026-16264"]
title: "Malicious code in aiosendletter (PyPI)"
severity: "critical"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: [{"name": "aiosendletter", "fixed": [], "affected": "= 0.2.0; = 3.7; = 3.8; = 3.9; = 4.0; = 4.1; = 4.3; = 4.5; = 4.6", "ecosystem": "pypi"}]
ecosystems: ["pypi"]
tags: ["malicious", "package"]
not_affected_if: []
published_at: "2026-09-17T19:40:07+00:00"
first_seen_at: "2026-10-26T20:51:57+00:00"
updated_at: "2026-10-26T21:10:31+00:00"
sources: [{"source": "osv-malicious", "url": "https://osv.dev/vulnerability/MAL-2026-16264", "first_seen_at": "2026-10-26T20:51:57+00:00"}]
---

# Malicious code in aiosendletter (PyPI)

## Affected

- pypi:aiosendletter affected = 0.2.0; = 3.7; = 3.8; = 3.9; = 4.0; = 4.1; = 4.3; = 4.5; = 4.6 fixed ?

## Timeline

- 2026-10-26T20:51:57+00:00 osv-malicious https://osv.dev/vulnerability/MAL-2026-16264

## From the sources

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_-= 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

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