Answer in brief
CVE-2026-43974 records a High severity security vulnerability in gun has an Unexpected Status Code or Return Value vulnerability. The source record does not mark it as known exploited. 1 affected package is mapped in the feed.
Answer in brief
CVE-2026-43974 records a High severity security vulnerability in gun has an Unexpected Status Code or Return Value vulnerability. The source record does not mark it as known exploited. 1 affected package is mapped in the feed.
Update gun to 2.4.0 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanVulnerability describes the vulnerability class recorded for this advisory. The current record does not mark CVE-2026-43974 as known exploited; continue to monitor the source for status changes. The feed includes package mappings that can be checked against lockfiles and deployed manifests.
| Package | Affected range | Fixed version |
|---|---|---|
| gunerlang | >=2.0.0,<2.4.0 | 2.4.0 |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
CVE-2026-43974 records a High severity security vulnerability in gun has an Unexpected Status Code or Return Value vulnerability. The source record does not mark it as known exploited. 1 affected package is mapped in the feed.
The source record does not mark it as known exploited.
Check lockfiles and deployed manifests for gun.
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL GuardUpdate gun to 2.4.0 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanVulnerability describes the vulnerability class recorded for this advisory. The current record does not mark CVE-2026-43974 as known exploited; continue to monitor the source for status changes. The feed includes package mappings that can be checked against lockfiles and deployed manifests.
| Package | Affected range | Fixed version |
|---|---|---|
| gunerlang | >=2.0.0,<2.4.0 | 2.4.0 |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
CVE-2026-43974 records a High severity security vulnerability in gun has an Unexpected Status Code or Return Value vulnerability. The source record does not mark it as known exploited. 1 affected package is mapped in the feed.
The source record does not mark it as known exploited.
Check lockfiles and deployed manifests for gun.
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL GuardUnexpected 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.
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.