Process crash via unbounded SMTP response accumulation
Published Sep 18, 2026 · Updated Sep 18, 2026
Resource exhaustion in Netty SmtpResponseDecoder allows remote attackers to crash affected Java processes via SMTP responses. The decoder appends every continuation-line detail to a per-connection ArrayList without a count or cumulative-size limit and clears it only after a terminator. Exploitation requires a malicious or man-in-the-middle SMTP server to withhold that terminator, causing heap exhaustion and an OutOfMemoryError.
Summary
What happened
Resource exhaustion in Netty SmtpResponseDecoder allows remote attackers to crash affected Java processes via SMTP responses. The decoder appends every continuation-line detail to a per-connection ArrayList without a count or cumulative-size limit and clears it only after a terminator. Exploitation requires a malicious or man-in-the-middle SMTP server to withhold that terminator, causing heap exhaustion and an OutOfMemoryError.
The record
- CVE
- CVE-2026-93563
- Published
- Sep 18, 2026
- Updated
- Sep 18, 2026
- Vendor
- Commonhaus Foundation
- Product
- Red Hat JBoss Enterprise Application Platform 7
- Classifications
- CWE-400, CWE-770, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 18, 2026CVE publishedPublication date reported by the CVE source.
- Sep 18, 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
- SMTP continuation-line heap-exhaustion proof of conceptproof of concept · unverified
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Technologies
Your stack
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