PYSEC-2026-3626
Vulnerability from pysec - Published: 2026-08-10 10:43 - Updated: 2026-08-10 11:01Summary
WebhookHandler.feed_update() deserializes the entire request body before verifying the HMAC signature. This allows an unauthenticated attacker to force expensive parsing of arbitrary JSON payloads that will ultimately be rejected, leading to unnecessary CPU and memory consumption.
Severity
High (CVSS 7.5)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected Package
- Ecosystem: PyPI
- Package:
aiosend
Affected Versions
< 3.0.6
Patched Versions
>= 3.0.6
Details
In aiosend/webhook/base.py, WebhookHandler.feed_update() performs full Pydantic deserialization before validating the webhook signature:
update = Update.model_validate(body, context={"client": self})
if not self._check_signature(body, headers):
return False
Because authentication occurs only after parsing, anyone can send arbitrarily large JSON payloads with an invalid signature. Although the request is rejected, the server still performs all parsing work.
Additionally, CryptoPayObject is configured with:
ConfigDict(extra="allow")
allowing arbitrary extra fields to be retained in memory, increasing resource consumption.
Impact
An unauthenticated attacker can repeatedly send large invalid webhook requests, forcing the server to consume CPU time and memory before rejecting them.
This results in a pre-authentication denial-of-service condition affecting all webhook integrations.
Affected Components
aiosend/webhook/base.pyaiosend/types/base.pyAiohttpManagerFastAPIManagerFlaskManager
Workarounds
Until upgrading:
- Restrict request body size at the reverse proxy or web framework.
- Rate-limit webhook endpoints.
- Reject oversized requests before JSON parsing.
Solution
Upgrade to aiosend 3.0.6 or later.
CWE
- CWE-400: Uncontrolled Resource Consumption
| Name | purl | aiosend | pkg:pypi/aiosend |
|---|
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "aiosend",
"purl": "pkg:pypi/aiosend"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.0.7"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"0.1.14",
"0.1.15",
"1.0.0",
"1.0.1",
"1.0.2",
"1.0.3",
"2.0.0",
"2.0.1",
"2.0.2",
"2.0.3",
"2.0.4",
"2.0.5",
"2.0.6",
"2.1.0",
"2.1.1",
"2.1.2",
"2.1.3",
"3.0.0",
"3.0.1",
"3.0.2",
"3.0.4",
"3.0.5",
"3.0.6"
]
}
],
"aliases": [
"CVE-2026-70646",
"GHSA-7m8f-hgjq-8gc9"
],
"details": "## Summary\n\n`WebhookHandler.feed_update()` deserializes the entire request body before verifying the HMAC signature. This allows an unauthenticated attacker to force expensive parsing of arbitrary JSON payloads that will ultimately be rejected, leading to unnecessary CPU and memory consumption.\n\n## Severity\n\n**High** (CVSS 7.5)\n\n```\nCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\n```\n\n## Affected Package\n\n- Ecosystem: PyPI\n- Package: `aiosend`\n\n## Affected Versions\n\n- `\u003c 3.0.6`\n\n## Patched Versions\n\n- `\u003e= 3.0.6`\n\n## Details\n\nIn `aiosend/webhook/base.py`, `WebhookHandler.feed_update()` performs full Pydantic deserialization before validating the webhook signature:\n\n```python\nupdate = Update.model_validate(body, context={\"client\": self})\nif not self._check_signature(body, headers):\n return False\n```\n\nBecause authentication occurs only after parsing, anyone can send arbitrarily large JSON payloads with an invalid signature. Although the request is rejected, the server still performs all parsing work.\n\nAdditionally, `CryptoPayObject` is configured with:\n\n```python\nConfigDict(extra=\"allow\")\n```\n\nallowing arbitrary extra fields to be retained in memory, increasing resource consumption.\n\n## Impact\n\nAn unauthenticated attacker can repeatedly send large invalid webhook requests, forcing the server to consume CPU time and memory before rejecting them.\n\nThis results in a pre-authentication denial-of-service condition affecting all webhook integrations.\n\n## Affected Components\n\n- `aiosend/webhook/base.py`\n- `aiosend/types/base.py`\n- `AiohttpManager`\n- `FastAPIManager`\n- `FlaskManager`\n\n## Workarounds\n\nUntil upgrading:\n\n- Restrict request body size at the reverse proxy or web framework.\n- Rate-limit webhook endpoints.\n- Reject oversized requests before JSON parsing.\n\n## Solution\n\nUpgrade to **aiosend 3.0.6** or later.\n\n## CWE\n\n- CWE-400: Uncontrolled Resource Consumption",
"id": "PYSEC-2026-3626",
"modified": "2026-08-10T11:01:33.207387Z",
"published": "2026-08-10T10:43:48.956879Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/vovchic17/aiosend/security/advisories/GHSA-7m8f-hgjq-8gc9"
},
{
"type": "WEB",
"url": "https://github.com/vovchic17/aiosend/commit/db20f0a742209dfac181863d398ec5112687efa4"
},
{
"type": "PACKAGE",
"url": "https://github.com/vovchic17/aiosend"
},
{
"type": "WEB",
"url": "https://github.com/vovchic17/aiosend/releases/tag/v3.0.7"
},
{
"type": "PACKAGE",
"url": "https://pypi.org/project/aiosend"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-7m8f-hgjq-8gc9"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-70646"
}
],
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "aiosend: Deserialization of request body before signature verification (Pre-auth DoS) in webhook handler"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.