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CVE-2026-48521

📛 CVE Title

Envoy: HTTP/3 connection pool selection null-derefs in ProdClusterManagerFactory::allocateConnPool when transport_socket_options is null

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Description

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy's ProdClusterManagerFactory::allocateConnPool dereferences transport_socket_options while selecting an HTTP/3 connection pool without first checking whether the pointer is null. LoadBalancerContext implementations used by synthetic, mirror, health-check, and async-client calls can return no transport-socket options. With auto_config and HTTP/3 enabled, routine traffic reaching one of those contexts can crash an Envoy worker. The relevant scope boundary is that the affected branch requires HTTP/3 in the protocol set and a context that supplies no transport-socket options. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.

Overview

State
PUBLISHED
Assigner (CNA)
GitHub_M
CVSS severity
MEDIUM
CVSS score
CVSS 5.9 / 10 5.9 5.9 / 10
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Effective score
5.9 / 10 MEDIUM source: CNA overview
CWE(s)
CWE-476
Reserved
2026-05-21
Published
2026-09-21 19:44 UTC
Last updated
2026-09-21 20:04 UTC
Source
https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/48xxx/CVE-2026-48521.json

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
2026-09-21 20:17:25 UTC
NVD last modified
2026-09-21 20:17:25 UTC
NVD CVSS v3.1
CVSS 5.9 / 10 5.9 5.9 / 10 MEDIUM source: security-advisories@github.com
NVD CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Exploitability subscore
2.2 / 10
Impact subscore
3.6 / 10

NVD / KEV / EPSS data refreshed 2026-09-22 03:40 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-2026-84109
Assigner
GitHub_M
Published
Sep 21, 2026, 7:44:15 PM
Updated
Sep 21, 2026, 8:04:16 PM
EUVD base score (CVSS 3.1)
5.9 / 10
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
EUVD-reported EPSS
0.0000
Vendors
envoyproxy
Products
envoy (< 1.36.10)
envoy (1.37.0, < 1.37.6)
envoy (1.38.0, < 1.38.4)
envoy (1.39.0, < 1.39.1)

ENISA description: Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy's ProdClusterManagerFactory::allocateConnPool dereferences transport_socket_options while selecting an HTTP/3 connection pool without first checking whether the pointer is null. LoadBalancerContext implementations used by synthetic, mirror, health-check, and async-client calls can return no transport-socket options. With auto_config and HTTP/3 enabled, routine traffic reaching one of those contexts can crash an Envoy worker. The relevant scope boundary is that the affected branch requires HTTP/3 in the protocol set and a context that supplies no transport-socket options. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.

EUVD references (9)

Affected products (1)
VendorProductVersionsPlatforms
envoyproxy envoy < 1.36.10 (affected), >= 1.37.0, < 1.37.6 (affected), >= 1.38.0, < 1.38.4 (affected), >= 1.39.0, < 1.39.1 (affected) —

Vendor references (9)

References embedded in the original CVE record by the assigning CNA.

Web references (0)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

No web references attached yet.

NVD-tagged references (10)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

Remediations (10)

  • Microsoft Update Catalog
    web:catalog.update.microsoft.com

    Welcome to the Microsoft Update Catalog site. We want your feedback! Visit our newsgroup or send us an email to provide us with your thoughts and suggestions. To get started using the site, enter in your search terms in the Search box above or visit our FAQ for search tips. |Newsgroup|Send us your feedback

    2026-09-22 17:11 UTC
  • Security Update Guide - Microsoft
    web:msrc.microsoft.com

    The Microsoft Security Response Center (MSRC) investigates all reports of security vulnerabilities affecting Microsoft products and services, and provides the information here as part of the ongoing effort to help you manage security risks and help keep your systems protected.

    2026-09-22 17:11 UTC
  • Security Update Guide - Microsoft Security Response Center
    web:msrc.microsoft.com

    Access Microsoft Security Response Center's guide to address vulnerabilities, manage security risks, and keep your systems protected with the latest updates.

    2026-09-22 17:11 UTC
  • Cisco Advance Notification for Publication of September 16, 2026 ...
    web:sec.cloudapps.cisco.com

    On September 16, 2026 , the Cisco Product Security Incident Response Team (PSIRT) published the advisories that are listed in the following tables. To remediate these vulnerabilities, Cisco strongly recommends that customers upgrade to the fixed software that is indicated in the advisories. For more information about changes in Cisco PSIRT vulnerability disclosure, see Strengthening the ...

    2026-09-22 17:11 UTC
  • Microsoft Patch Tracker (September 2026): Exploit-Ranked | Senserva
    web:senserva.com

    Every Microsoft security patch (KB) and the CVEs it fixes, with severity, CVSS, and CISA KEV status. Cross-linked to the CVE reference.

    2026-09-22 17:11 UTC
  • SAP Security Patch Day - April 2026
    web:support.sap.com

    SAP security patch day bulletin This post shares the information on security notes that remediate vulnerabilities discovered in SAP products. SAP strongly recommends that the customer visits the support portal and applies patches on priority to protect their SAP landscape. On 14 th of April 2026 , SAP security patch day saw the release of 19 new security notes. There is 1 update to previously ...

    2026-09-22 17:11 UTC
  • SAP Security Patch Day - May 2026
    web:support.sap.com

    SAP security Patch Day Bulletin This post shares the information on security notes that remediate vulnerabilities discovered in SAP products. SAP strongly recommends that the customer visits the support portal and applies patches on priority to protect their SAP landscape. On 12 th of May 2026 , SAP security patch day saw the release of 15 new security notes.

    2026-09-22 17:11 UTC
  • The 8 Best Automated Vulnerability Remediation Tools in 2026
    web:www.openhands.dev

    Compare 8 automated vulnerability remediation tools for 2026 on fixes, prioritization, integrations, and deployment control.

    2026-09-22 17:11 UTC
  • Oracle Critical Patch Update Advisory - April 2026
    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.

    2026-09-22 17:11 UTC
  • Oracle Critical Patch Update Advisory - July 2026
    web:www.oracle.com

    This Critical Patch Update contains 1448 new security patches across the product families listed below. Please note that a My Oracle Support (MOS) note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at July 2026 Critical Patch Update: Executive Summary and Analysis.

    2026-09-22 17:11 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-48521.json.

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