CVE-2024-34083
📋 TL;DR
This vulnerability in aiosmtpd allows man-in-the-middle attackers to inject unencrypted SMTP commands after STARTTLS negotiation, which are then processed as if they came from within the encrypted connection. This affects all servers using vulnerable versions of aiosmtpd with STARTTLS enabled. The attack enables command injection and potential authentication bypass.
💻 Affected Systems
- aiosmtpd
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Attackers could inject malicious SMTP commands to read/write emails, impersonate users, or compromise mail server integrity.
Likely Case
Unauthorized email sending, email interception, or authentication bypass in SMTP transactions.
If Mitigated
Limited impact with proper network segmentation and monitoring, though vulnerability remains.
🎯 Exploit Status
Requires man-in-the-middle position on network. Proof-of-concept available in advisory references.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.4.6
Vendor Advisory: https://github.com/aio-libs/aiosmtpd/security/advisories/GHSA-wgjv-9j3q-jhg8
Restart Required: Yes
Instructions:
1. Update aiosmtpd: pip install --upgrade aiosmtpd==1.4.6
2. Restart all aiosmtpd services
3. Verify version with: python -c "import aiosmtpd; print(aiosmtpd.__version__)"
🔧 Temporary Workarounds
Disable STARTTLS
allUse only plain SMTP or enforce TLS from connection start instead of STARTTLS upgrade
Configure SMTP server to disable STARTTLS in aiosmtpd configuration
Network Segmentation
allRestrict SMTP traffic to trusted networks only
Configure firewall rules to limit SMTP port 587 access
🧯 If You Can't Patch
- Implement strict network monitoring for anomalous SMTP command sequences
- Use external TLS termination (e.g., stunnel, haproxy) instead of aiosmtpd's STARTTLS
🔍 How to Verify
Check if Vulnerable:
Check aiosmtpd version: python -c "import aiosmtpd; print(aiosmtpd.__version__)" - if version < 1.4.6 and STARTTLS is enabled, system is vulnerable.Check Version:
python -c "import aiosmtpd; print(aiosmtpd.__version__)"Verify Fix Applied:
Confirm version is 1.4.6 or higher and test STARTTLS functionality with SMTP client.📡 Detection & Monitoring
Log Indicators:
- Unexpected SMTP commands after STARTTLS
- Authentication attempts from unexpected sources after STARTTLS
Network Indicators:
- Unencrypted SMTP traffic on port 587 after STARTTLS initiation
- Multiple command injections in single SMTP session
SIEM Query:
source="mail.log" AND "STARTTLS" AND ("AUTH" OR "MAIL FROM" OR "RCPT TO") within 1 second🔗 References
- https://github.com/aio-libs/aiosmtpd/commit/b3a4a2c6ecfd228856a20d637dc383541fcdbfda
- https://github.com/aio-libs/aiosmtpd/security/advisories/GHSA-wgjv-9j3q-jhg8
- https://nostarttls.secvuln.info
- https://github.com/aio-libs/aiosmtpd/commit/b3a4a2c6ecfd228856a20d637dc383541fcdbfda
- https://github.com/aio-libs/aiosmtpd/security/advisories/GHSA-wgjv-9j3q-jhg8
- https://nostarttls.secvuln.info
