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Nginx Plus EUVDEUVD-2026-78585

| CVE-2026-90439 MEDIUM
Heap-based Buffer Overflow (CWE-122)
2026-09-15 f5 GHSA-fjgw-pmcm-g7j7
6.9
CVSS 4.0 · Vendor: f5
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Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Heap buffer bounds checking
MITRE ATT&CK

1 technique across 1 tactic: Execution

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 15, 2026

Heap buffer overflow in the NGINX HTTP/3 module (ngx_http_v3_module) can crash NGINX worker processes or corrupt a limited amount of heap data when NGINX Plus or NGINX Open Source serves QUIC traffic while linked against OpenSSL 3.5.0 or earlier under certain configurations. The overflow occurs while processing a TLS handshake and is non-deterministic — triggering it is largely outside the attacker's control — so the realistic outcome is opportunistic denial of service (worker restart) plus limited data corruption rather than reliable remote code execution. There is no control plane exposure (data plane only), no public exploit identified at time of analysis, and no CISA KEV listing; EPSS data was not provided.

Affected VersionsENISA

NGINX Open Source 1.29.2 <1.31.6
NGINX Plus 37.0.0.1 <37.0.6.1
NGINX Open Source 1.30.4 <1.30.5
NGINX Plus 37.1.0.1 <37.1.1.1

Affected Packages

euvd nginx_open_source fix: 1.30.5, 1.31.6
euvd nginx_plus fix: 37.0.6.1, 37.1.1.1

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 2 packages in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (f5) PRIMARY 6.9 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
SUSE MEDIUM
Red Hat 6.5 MEDIUM

Primary rating from Vendor (f5).

CVSS VectorVendor: f5

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Vulnerable system: Confidentiality
None
Vulnerable system: Integrity
Low
Vulnerable system: Availability
Low
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

Lifecycle Timeline

3
CVSS changed
Sep 15, 2026 - 15:22 NVD
6.5 (MEDIUM) 6.9 (MEDIUM)
Patch available
Sep 15, 2026 - 15:17 EUVD
CVE Published
Sep 15, 2026 - 14:27 cve.org
MEDIUM 6.5

DescriptionCVE.org

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_v3_module module. When using HTTP/3 with OpenSSL versions <= OpenSSL 3.5.0 under certain configurations, a limited heap buffer overflow could happen while processing a TLS handshake. This can happen in a non-deterministic manner that is beyond the attacker's control. This may cause a heap buffer overflow in the NGINX worker process leading to a restart and/or limited data corruption.

Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or limited data corruption. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Threat Intelligence Overview

EPSS Score
0.3%
Top 83% exploitable
Data Quality
5 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.3%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
Yes
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

34
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +34
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

A heap overflow occurs when a program writes data beyond the bounds of a buffer allocated in the heap memory region.

CVE-2023-44487 HIGH POC
7.5 Oct 10

Denial of service against HTTP/2 server implementations allows remote unauthenticated attackers to exhaust server resour

CVE-2026-42945 CRITICAL POC
9.2 May 13

Heap buffer overflow in NGINX Plus and NGINX Open Source ngx_http_rewrite_module allows remote attackers to crash worker

CVE-2026-42055 CRITICAL POC
9.2 Jun 17

Heap-based buffer overflow in NGINX Plus and NGINX Open Source affects deployments that proxy HTTP/2 or gRPC traffic ups

CVE-2026-9256 CRITICAL POC
9.2 May 22

Heap buffer overflow in NGINX Plus and NGINX Open Source ngx_http_rewrite_module can be triggered by unauthenticated rem

CVE-2026-42533 CRITICAL POC
9.2 Jul 15

Heap buffer overflow in NGINX Plus and NGINX Open Source lets unauthenticated remote attackers crash worker processes (D

CVE-2026-93479 CRITICAL POC
9.2 Oct 14

Heap buffer overflow in NGINX Plus and NGINX Open Source can be triggered by crafted HTTP requests when a non-default ma

CVE-2026-15176 CRITICAL POC
9.2 Oct 14

Heap buffer overflow in NGINX Plus and NGINX Open Source can be triggered by unauthenticated remote attackers through cr

CVE-2026-97205 CRITICAL POC
9.2 Oct 14

Unauthenticated remote attackers can trigger a use-after-free in NGINX's ngx_http_core_module when asynchronous file I/O

CVE-2026-60005 HIGH
8.8 Jul 15

Limited memory disclosure and worker-process restart in NGINX Plus and NGINX Open Source arise when the optional ngx_htt

CVE-2026-27654 HIGH POC
8.8 Mar 24

Buffer overflow in NGINX's DAV module allows remote attackers to crash worker processes or manipulate file names outside

CVE-2026-27651 HIGH
8.7 Mar 24

NGINX worker process crashes via null pointer dereference in the mail authentication module when CRAM-MD5 or APOP authen

CVE-2024-39792 HIGH
8.7 Aug 14

When the NGINX Plus is configured to use the MQTT pre-read module, undisclosed requests can cause an increase in memory

Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
openSUSE Tumbleweed Fixed
SUSE Linux Enterprise Module for Server Applications 15 SP7 Affected
SUSE Linux Enterprise Server 15 SP7 Affected
SUSE Linux Enterprise Server 16.0 Affected
SUSE Linux Enterprise Server 16.1 Affected

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