EEF-CVE-2026-43974
- Source
- https://cna.erlef.org/osv/EEF-CVE-2026-43974.html
- Import Source
- https://cna.erlef.org/osv/EEF-CVE-2026-43974.json
- JSON Data
- https://api.osv.dev/v1/vulns/EEF-CVE-2026-43974
- Aliases
- Published
- 2026-06-08T14:12:36.957Z
- Modified
- 2026-08-03T18:23:32.058849641Z
- Severity
-
- 8.7 (High) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N CVSS Calculator
- Summary
- gun HTTP/1.1 client accepts unsolicited 101 Switching Protocols response allowing server-driven protocol hijack and OOM
- Details
-
Summary
Unexpected Status Code or Return Value vulnerability in ninenines gun (gun_http module) allows a malicious HTTP server to force the client into raw protocol mode via an unsolicited 101 Switching Protocols response.
In gun_http:handle_inform/8, when a 101 Switching Protocols response is received over HTTP/1.1, the function verifies only that the Upgrade header is syntactically valid and that the stream reference is a plain reference(). It does not check whether the client ever sent an Upgrade or Connection: upgrade header on the corresponding request. Because this check is absent, any 101 response (solicited or not) causes gun to dispatch a gun_upgrade message to the caller and transition the entire connection to raw protocol mode.
A malicious or compromised HTTP server can send an unsolicited 101 response to any HTTP/1.1 request, causing the gun client to abandon HTTP framing for that connection. Once in raw mode, gun_raw applies no flow control (flow=infinity) and re-arms socket active mode after every received packet, so the server can flood the client with arbitrary bytes. These are forwarded as unbounded gun_data messages to the owner process, exhausting its mailbox and BEAM memory, ultimately crashing the VM.
This issue affects gun: from 2.0.0 before 2.4.0.
- Database specific
{ "cwe_ids": [ "CWE-841" ], "cpe_ids": [ "cpe:2.3:a:ninenines:gun:*:*:*:*:*:*:*:*" ], "capec_ids": [ "CAPEC-220", "CAPEC-130" ] }- References
- Credits
-
-
- Peter Ullrich - FINDER
-
- Loïc Hoguin - REMEDIATION_DEVELOPER
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Affected packages
Hex / gun
Package
- Name
- gun
- Purl
- pkg:hex/gun