CVE-2026-43974 (GCVE-0-2026-43974)

Vulnerability from cvelistv5 – Published: 2026-06-08 14:12 – Updated: 2026-06-08 16:34
VLAI?
Title
gun HTTP/1.1 client accepts unsolicited 101 Switching Protocols response allowing server-driven protocol hijack and OOM
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.
Severity ?
8.7 (High)
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
CWE
  • CWE-841 - Improper Enforcement of Behavioral Workflow
Assigner
EEF
References
Impacted products
Vendor Product Version
ninenines gun Affected: 2.0.0 , < 2.4.0 (semver)
    cpe:2.3:a:ninenines:gun:*:*:*:*:*:*:*:*
 Create a notification for this product.
    ninenines gun Affected: a3c2edbb8c807717e2f10520c6cf1e77a62eab2e , < 5b48068c29ce5e112cb149b5857c7d4dc319a81b (git)
    cpe:2.3:a:ninenines:gun:*:*:*:*:*:*:*:*
 Create a notification for this product.
Credits
Peter Ullrich Loïc Hoguin
Show details on NVD website
To clipboard 

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