CVE-2026-43973
📛 CVE Title
gun HTTP/1.1 response buffer has no size limit allowing server-controlled memory exhaustion
Description
Uncontrolled Resource Consumption vulnerability in ninenines gun (gun_http module) allows a malicious server to exhaust client memory via unbounded HTTP/1.1 response buffering. In gun_http:handle/5, three clauses accumulate incoming TCP data into the connection's buffer field using binary concatenation with no upper-bound check: the head clause appends data until the \r\n\r\n header terminator is found; the body_chunked clause appends data whenever cow_http_te:stream_chunked/2 returns a more result indicating an incomplete chunk boundary; and the body_trailer clause appends data until the trailing \r\n\r\n is found. In each case, when the expected terminator never arrives, the enlarged binary is stored back into state and the process waits for more data, with no configurable or hard-coded ceiling on buffer size. A malicious or compromised server can exploit this by sending a partial response that never completes. For example, a response may begin with HTTP/1.1 200 OK\r\nX-Pad: followed by an unbounded stream of arbitrary bytes, never sending the header terminator. The gun connection process will continuously append the incoming data to its buffer, causing unbounded heap growth. Because BEAM imposes no per-process heap limit by default, a single malicious connection can exhaust all available memory on the node, causing a node-wide out-of-memory crash. This issue affects gun: from 1.0.0 before 2.4.0.
Overview
- State
- —
- Assigner (CNA)
- —
- CVSS severity
- high
- CVSS score
- 7.5 / 10
- CVSS vector
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Effective score
- 7.5 / 10 HIGH source: CNA overview
- CWE(s)
-
CWE-770 - Reserved
- —
- Published
- 2026-06-09 07:00 UTC
- Last updated
- 2026-06-20 01:43 UTC
- Source
- https://www.tenable.com/cve/CVE-2026-43973
- Linked Threat
- CVE-2026-43973 — CVE-2026-43973
NVD triage scoring NVD CVE 2.0
Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.
- NVD published
- 2026-06-08 15:16:46 UTC
- NVD last modified
- 2026-07-23 07:10:00 UTC
- EPSS score
- 0.0038 (probability of exploitation in next 30 days)
- EPSS percentile
- 30.82% vs all CVEs — higher = more likely to be exploited, as of 2026-08-01
NVD / KEV / EPSS data refreshed 2026-08-01 16:30 UTC. Re-run the 🛰 Backfill from NVD button above to refresh.
European Union Vulnerability Database ENISA EUVD
ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.
- EUVD ID
-
EUVD-2026-35074 - Assigner
- EEF
- Published
- Jun 8, 2026, 2:12:42 PM
- Updated
- Jun 8, 2026, 4:35:01 PM
- EUVD base score (CVSS 4.0)
-
8.7 / 10
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 - EUVD-reported EPSS
- 0.3800
- Vendors
- ninenines
- Products
-
gun (1.0.0 <2.4.0)gun (11dfe71f4b9aedaaedea2ad3b2f32fd006a8480f <f3e7e0568b3c4cf9fa4bea79d5116e67ce76ad25)
- Aliases
-
GHSA-r53j-fjj5-mv77
ENISA description: Uncontrolled Resource Consumption vulnerability in ninenines gun (gun_http module) allows a malicious server to exhaust client memory via unbounded HTTP/1.1 response buffering. In gun_http:handle/5, three clauses accumulate incoming TCP data into the connection's buffer field using binary concatenation with no upper-bound check: the head clause appends data until the \r\n\r\n header terminator is found; the body_chunked clause appends data whenever cow_http_te:stream_chunked/2 returns a more result indicating an incomplete chunk boundary; and the body_trailer clause appends data until the trailing \r\n\r\n is found. In each case, when the expected terminator never arrives, the enlarged binary is stored back into state and the process waits for more data, with no configurable or hard-coded ceiling on buffer size. A malicious or compromised server can exploit this by sending a partial response that never completes. For example, a response may begin with HTTP/1.1 200 OK\r\nX-Pad: followed by an unbounded stream of arbitrary bytes, never sending the header terminator. The gun connection process will continuously append the incoming data to its buffer, causing unbounded heap growth. Because BEAM imposes no per-process heap limit by default, a single malicious connection can exhaust all available memory on the node, causing a node-wide out-of-memory crash. This issue affects gun: from 1.0.0 before 2.4.0.
Microsoft Security Response Center MSRC
Microsoft's vendor-authoritative record from the Security Update Guide — its own CVSS score, impact, severity rating, exploit assessment, and KB-article fixes. Refreshed 2026-07-23 03:00 UTC (source: CVRF).
- MS severity
- Moderate
- Release
- 2026-Jun
Microsoft remediations / KB articles (2)
- CBL-Mariner Releases — Vendor Fix / Security Update (fixed build 3.13.7-6)
- https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade — None Available / CBL-Mariner Releases
Vendor references (0)
References embedded in the original CVE record by the assigning CNA.
None in the CVE record.
Web references (7)
DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.
- None Available msrc
- MSRC update guide: CVE-2026-43973 msrc
- https://github.com/ninenines/gun/commit/f3e7e0568b3c4cf9fa4bea79d5116e67ce76ad25 tenable:github.com
- https://cna.erlef.org/cves/CVE-2026-43973.html tenable:cna.erlef.org
- https://nvd.nist.gov/vuln/detail/CVE-2026-43973 tenable:nvd.nist.gov
- https://osv.dev/vulnerability/EEF-CVE-2026-43973 tenable:osv.dev
- https://www.cve.org/CVERecord?id=CVE-2026-43973 tenable:www.cve.org
NVD-tagged references (3)
Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.
- https://cna.erlef.org/cves/CVE-2026-43973.html 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
- https://github.com/ninenines/gun/commit/f3e7e0568b3c4cf9fa4bea79d5116e67ce76ad25 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
- https://osv.dev/vulnerability/EEF-CVE-2026-43973 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Remediations (10)
Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.
-
web:cybersecuritynews.com
Microsoft has officially acknowledged a critical zero-day vulnerability in Microsoft Defender, publicly dubbed "RoguePlanet," and confirmed it is actively developing a security patch to address the flaw.
2026-06-19 02:37 UTC -
web:nvd.nist.gov
Official websites use .gov A .gov website belongs to an official government organization in the United States.
2026-06-19 02:37 UTC -
web:portal.msrc.microsoft.com
The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.
2026-06-19 02:37 UTC -
web:support.microsoft.com
Applies to: Windows Server 2019 This security update includes fixes and quality improvements that are part of the following update: May 12, 2026—KB5087538 (OS Build 17763.8755) The following is a summary of the issues that this update addresses when you install this update. The bold text within the brackets indicates the item or area of the change we are documenting. [Secure Boot] This ...
2026-06-19 02:37 UTC -
web:www.computerworld.com
Microsoft says it is considering a patch for a zero-day vulnerability, dubbed YellowKey, that allows attackers with access to a Windows device to bypass Bitlocker encryption protection and read ...
2026-06-19 02:37 UTC -
web:www.malwarebytes.com
Microsoft says it's working on a fix for an unpatched Defender vulnerability that can give attackers the highest level of access on Windows.
2026-06-19 02:37 UTC -
web:www.oracle.com
This Critical Patch Update contains 481 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at April 2026 Critical Patch Update: Executive Summary and Analysis.
2026-06-19 02:37 UTC -
web:www.oracle.com
This Critical Security Patch Update contains 35 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Security Patch Update and other Oracle Software Security Assurance activities is located at May 2026 Critical Security Patch Update: Executive Summary and Analysis.
2026-06-19 02:37 UTC -
web:www.rapid7.com
Microsoft is publishing 200 vulnerabilities on June 2026 Patch Tuesday, including an HTTP/2 denial of service vulnerability and an elevation of privilege vulnerability in PowerToys.
2026-06-19 02:37 UTC -
web:zecurit.com
Get the complete breakdown of Microsoft's June 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .
2026-06-19 02:37 UTC
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