Remote code execution via NTLM challenge overflow
Published Sep 21, 2026 · Updated Sep 21, 2026
Stack-based buffer overflow in fetchmail 5.0.8 through 6.6.6 allows remote attackers to corrupt memory via a crafted NTLM challenge. The buildSmbNtlmAuthReponse path uses AddBytes to copy server-controlled challenge data into a fixed stack response buffer without checking remaining capacity. An NTLM-enabled build and attacker-controlled server are required; favorable compiler stack layout permits code execution, while other layouts cause authentication failure or process termination.
Summary
What happened
Stack-based buffer overflow in fetchmail 5.0.8 through 6.6.6 allows remote attackers to corrupt memory via a crafted NTLM challenge. The buildSmbNtlmAuthReponse path uses AddBytes to copy server-controlled challenge data into a fixed stack response buffer without checking remaining capacity. An NTLM-enabled build and attacker-controlled server are required; favorable compiler stack layout permits code execution, while other layouts cause authentication failure or process termination.
The record
- CVE
- CVE-2026-94184
- Published
- Sep 21, 2026
- Updated
- Sep 21, 2026
- Vendor
- Commonhaus Foundation
- Product
- Red Hat Enterprise Linux 10
- Classifications
- CWE-121, T1203
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 21, 2026CVE publishedPublication date reported by the CVE source.
- Sep 21, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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