Unauthenticated service crash via recursive JSON parsing
Published Jun 9, 2026 · Updated Jun 9, 2026
Uncontrolled recursion in FreeSWITCH before 1.11.1 allows remote attackers to crash the service through a crafted WebSocket JSON frame. The pre-authentication mod_verto frame handler passes raw frame data to cJSON_Parse, whose recursive descent exhausts the 240 KiB worker stack before its 1,000-level limit. Network reach to a mod_verto listener is sufficient; the resulting guard-page SIGSEGV terminates every call and session on the host without enabling a write primitive.
Summary
What happened
Uncontrolled recursion in FreeSWITCH before 1.11.1 allows remote attackers to crash the service through a crafted WebSocket JSON frame. The pre-authentication mod_verto frame handler passes raw frame data to cJSON_Parse, whose recursive descent exhausts the 240 KiB worker stack before its 1,000-level limit. Network reach to a mod_verto listener is sufficient; the resulting guard-page SIGSEGV terminates every call and session on the host without enabling a write primitive.
The record
- CVE
- CVE-2026-49847
- Published
- Jun 9, 2026
- Updated
- Jun 9, 2026
- Vendor
- SignalWire
- Product
- FreeSWITCH
- Classifications
- CWE-674, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 9, 2026CVE publishedPublication date reported by the CVE source.
- Jun 9, 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=< 1.11.1
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
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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