CVE-2026-88840

Description

BusyBox TLS get_client_hello() reads past the end of the input buffer when parsing a truncated ClientHello message.

Overview

State: PUBLISHED
Assigner (CNA): redhat
CVSS severity: MEDIUM
CVSS score: 5.3 / 10
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Effective score: 5.3 / 10 MEDIUM source: CNA overview
CWE(s): CWE-125
Reserved: 2026-09-10
Published: 2026-09-23 17:45 UTC
Last updated: 2026-09-23 17:45 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/88xxx/CVE-2026-88840.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: 2026-09-23 18:17:10 UTC
NVD last modified: 2026-09-23 19:40:10 UTC
NVD CVSS v3.1: 5.3 / 10 MEDIUM source: secalert@redhat.com
NVD CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Exploitability subscore: 3.9 / 10
Impact subscore: 1.4 / 10

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-2026-85513
Assigner: redhat
Published: Sep 23, 2026, 5:45:34 PM
Updated: Sep 23, 2026, 5:45:34 PM
EUVD base score (CVSS 3.1): 5.3 / 10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
EUVD-reported EPSS: 0.0000
Aliases: GHSA-w878-vhh4-m5pv

ENISA description: BusyBox TLS get_client_hello() reads past the end of the input buffer when parsing a truncated ClientHello message.

EUVD references (2)

Affected products (1)

Vendor	Product	Versions	Platforms
Red Hat	Red Hat Hardened Images	—	—

Vendor references (2)

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

https://access.redhat.com/security/cve/CVE-2026-88840 vdb-entryx_refsource_REDHAT
RHBZ#2531354 issue-trackingx_refsource_REDHAT

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 (2)

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://access.redhat.com/security/cve/CVE-2026-88840 secalert@redhat.com
https://bugzilla.redhat.com/show_bug.cgi?id=2531354 secalert@redhat.com

Remediations (10)

CVE-2026-68820 Is in KEV. What BOD 26-04 Requires Now | Qualys

web:blog.qualys.com

Executive Summary CVE - 2026 -68820 is an actively exploited Windows vulnerability listed in CISA's Known Exploited Vulnerabilities (KEV) Catalog, with a remediation deadline as suggested by CISA BOD 26-04. CISA BOD 26-04 introduces risk-based remediation timelines ranging from 3 to 14 days, increasing the pressure on teams to move quickly from patch availability to verified remediation ...

2026-09-24 11:47 UTC
CISA Requires Federal Agencies to Patch Critical Vulnerabilities Within ...

web:cybersecuritynews.com

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has issued Binding Operational Directive (BOD) 26-04, titled "Prioritizing Security Updates Based on Risk," compelling all Federal Civilian Executive Branch (FCEB) agencies to remediate the most dangerous known exploited vulnerabilities within just three calendar days.

2026-09-24 11:47 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.

2026-09-24 11:47 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 ...

2026-09-24 11:47 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.

2026-09-24 11:47 UTC
August 2026 CVE Advisory Notification - Security

web:support.servicenow.com

Due to additional analysis provided by the security researcher who discovered CVE - 2026 -6876, we have upgraded the severity rating of CVE - 2026 -6876 from High to Critical. This change affects only the severity

2026-09-24 11:47 UTC
Microsoft August 2026 Patch Tuesday fixes 400 flaws, 3 zero-days

web:www.bleepingcomputer.com

Today is Microsoft's August 2026 Patch Tuesday, and with it comes security updates for a massive 400 flaws, including one actively exploited and two publicly disclosed zero-day vulnerabilities.

2026-09-24 11:47 UTC
Critical Patches Issued for Microsoft Products, August 11, 2026

web:www.cisecurity.org

<p>Multiple vulnerabilities have been discovered in Microsoft products, the most severe of which could allow for remote code execution. Successful exploitation of the most severe of these vulnerabilities could result in an attacker gaining the same privileges as the logged-on user. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or ...

2026-09-24 11:47 UTC
August's Patch Tuesday is a monster: 751 fixes, with an exploited ...

web:www.computerworld.com

August's Patch Tuesday is a big one: 751 fixes, an exploited WinSock flaw and plenty of critical Windows, Office and Exchange issues.

2026-09-24 11:47 UTC
Patch Tuesday September 2026: Security Updates & CVE Analysis

web:zecurit.com

Get the complete breakdown of Microsoft's September 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .

2026-09-24 11:47 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-88840.json.

{
  "containers": {
    "cna": {
      "affected": [
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:hummingbird:1"
          ],
          "defaultStatus": "affected",
          "packageName": "busybox",
          "product": "Red Hat Hardened Images",
          "vendor": "Red Hat"
        }
      ],
      "datePublic": "2026-09-23T16:35:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "BusyBox TLS get_client_hello() reads past the end of the input buffer when parsing a truncated ClientHello message."
        }
      ],
      "metrics": [
        {
          "other": {
            "content": {
              "namespace": "https://access.redhat.com/security/updates/classification/",
              "value": "Moderate"
            },
            "type": "Red Hat severity rating"
          }
        },
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
            "version": "3.1"
          },
          "format": "CVSS"
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-125",
              "description": "Out-of-bounds Read",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-23T17:45:34.724Z",
        "orgId": "53f830b8-0a3f-465b-8143-3b8a9948e749",
        "shortName": "redhat"
      },
      "references": [
        {
          "tags": [
            "vdb-entry",
            "x_refsource_REDHAT"
          ],
          "url": "https://access.redhat.com/security/cve/CVE-2026-88840"
        },
        {
          "name": "RHBZ#2531354",
          "tags": [
            "issue-tracking",
            "x_refsource_REDHAT"
          ],
          "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2531354"
        }
      ],
      "timeline": [
        {
          "lang": "en",
          "time": "2026-09-09T00:00:00.000Z",
          "value": "Reported to Red Hat."
        },
        {
          "lang": "en",
          "time": "2026-09-23T16:35:00.000Z",
          "value": "Made public."
        }
      ],
      "title": "Busybox: busybox: tls ssl_server reads one byte out of bounds when parsing truncated clienthello",
      "workarounds": [
        {
          "lang": "en",
          "value": "Do not use BusyBox ssl_server in production deployments. Upstream should add a bounds check to verify len > 0 before reading the compression-methods length byte."
        }
      ],
      "x_generator": {
        "engine": "cvelib 1.8.0"
      },
      "x_redhatCweChain": "CWE-125: Out-of-bounds Read"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "53f830b8-0a3f-465b-8143-3b8a9948e749",
    "assignerShortName": "redhat",
    "cveId": "CVE-2026-88840",
    "datePublished": "2026-09-23T17:45:34.724Z",
    "dateReserved": "2026-09-10T09:42:04.559Z",
    "dateUpdated": "2026-09-23T17:45:34.724Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}