Unauthenticated memory exhaustion via unbounded MCP sessions
Published Aug 25, 2026 · Updated Aug 25, 2026
Denial of service in the PraisonAI MCP HTTP server before 4.6.58 allows remote attackers to exhaust process memory via initialize requests. The mcp_post handler adds every initialize request to _sessions but neither calls _cleanup_sessions nor enforces a session limit, so entries persist for the process lifetime. Direct exploitation requires a routable server; the default localhost binding instead requires a victim to visit a malicious page that bypasses the Origin check, and sustained requests terminate the process.
Summary
What happened
Denial of service in the PraisonAI MCP HTTP server before 4.6.58 allows remote attackers to exhaust process memory via initialize requests. The mcp_post handler adds every initialize request to _sessions but neither calls _cleanup_sessions nor enforces a session limit, so entries persist for the process lifetime. Direct exploitation requires a routable server; the default localhost binding instead requires a victim to visit a malicious page that bypasses the Origin check, and sustained requests terminate the process.
The record
- CVE
- CVE-2026-55531
- Published
- Aug 25, 2026
- Updated
- Aug 25, 2026
- Vendor
- PraisonAI
- Product
- PraisonAI
- Classifications
- CWE-400, CWE-770, T1499.003
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 25, 2026CVE publishedPublication date reported by the CVE source.
- Aug 25, 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 4.6.58
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.
Weakness, pattern, technique
Public exploit references
- poc_mcp_session_dos.shproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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