CVE-2026-43974Network attack vector

VM crash via unsolicited protocol upgrade

Published Jun 8, 2026 · Updated Jun 8, 2026

Unexpected status handling in Nine Nines Gun 2.0.0 through 2.3.0 allows remote attackers to crash the BEAM VM via an HTTP/1.1 server. gun_http:handle_inform/8 accepts a syntactically valid 101 response without verifying that the request asked to upgrade, then switches the connection to raw mode. A malicious or compromised server must answer an HTTP/1.1 request; unlimited raw gun_data messages can exhaust the owner mailbox and memory until the VM crashes.

CVSS severity8.7
High
EPSS probability0.48%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unexpected status handling in Nine Nines Gun 2.0.0 through 2.3.0 allows remote attackers to crash the BEAM VM via an HTTP/1.1 server. gun_http:handle_inform/8 accepts a syntactically valid 101 response without verifying that the request asked to upgrade, then switches the connection to raw mode. A malicious or compromised server must answer an HTTP/1.1 request; unlimited raw gun_data messages can exhaust the owner mailbox and memory until the VM crashes.

The record

CVE
CVE-2026-43974
Published
Jun 8, 2026
Updated
Jun 8, 2026
Vendor
Nine Nines
Product
Gun
Classifications
CWE-841, CAPEC-130, CAPEC-220, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.0.0 <2.4.0
  2. Affected versionversion=a3c2edbb8c807717e2f10520c6cf1e77a62eab2e <5b48068c29ce5e112cb149b5857c7d4dc319a81b

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nine Nines · Gunversion=2.0.0 <2.4.0; version=a3c2edbb8c807717e2f10520c6cf1e77a62eab2e <5b48068c29ce5e112cb149b5857c7d4dc319a81b

Published CVSS scores

7.5NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.7Erlang Ecosystem FoundationCVSS: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 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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-841Improper Enforcement of Behavioral Workflow
CAPEC-130Excessive Allocation
CAPEC-220Client-Server Protocol Manipulation
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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