CVE-2026-70646 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in aiosend. A fix is available for aiosend — see the affected versions and patch details below.
aiosend: Deserialization of request body before signature verification (Pre-auth DoS) in webhook handler
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-70646.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
aiosendReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Summary
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
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | aiosend | all versions | 3.0.7pip install --upgrade 'aiosend==3.0.7' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for aiosend, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update aiosend to 3.0.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-70646 is resolved across your whole dependency graph.
Workarounds
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.
Frequently Asked Questions
Is CVE-2026-70646 in your dependencies?
Find it across PyPI, including transitive dependencies.