CVE-2026-115506ImportantNetworkRevised 26 Oct

libexpat through 2.9.0 Denial of Service via Billion Laughs Detection Delay

MSRC advisory NVD CVE.org

Assessment

Severity: Important
CVSS base score: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Impact: Not stated
EPSS, next 30 days: Not scored yet
Public exploit code: No Nuclei template lists it
Exploitability: Not assessed
Publicly disclosed: No
Customer action: Required: apply the update
Component: Mariner
Weakness: CWE-776: Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')
Issued by: VulnCheck
Published: 24 Oct 2026 · October 2026
Last revised: 26 Oct 2026Information published.

CVSS 3.1 base metricsRed raises the risk · green lowers it

Attack vector: NetworkAV:N
Attack complexity: LowAC:L
Privileges required: NonePR:N
User interaction: NoneUI:N
Scope: UnchangedS:U
Confidentiality: NoneC:N
Integrity: NoneI:N
Availability: HighA:H

Updates that fix it

0 KBs

No KB listed

MSRC lists no downloadable update, which usually means a service-side fix or a release-notes update. Check the MSRC advisory.

Affected products

2 affected products

azl3 cmake 3.30.3-15 on Azure Linux 3.0
azl3 expat 2.8.3-2 on Azure Linux 3.0

What changed

First observed 24 Oct 2026

26 Oct 2026 · 07:26:10 UTC Last revised25 Oct 2026 01:01 UTC → 26 Oct 2026 01:48 UTC
26 Oct 2026 · 07:26:10 UTC Affected productsazl3 expat 2.8.3-2 on Azure Linux 3.0 → azl3 cmake 3.30.3-15 on Azure Linux 3.0, azl3 expat 2.8.3-2 on Azure Linux 3.0
25 Oct 2026 · 07:41:18 UTC Last revised24 Oct 2026 01:01 UTC → 25 Oct 2026 01:01 UTC

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cve-program · CVE-2026-115506

Published

libexpat

Vendor product

Original vendor version evidence · not evaluated as a NuGet range

{
                    "vendor": "libexpat",
                    "product": "libexpat",
                    "packageURL": "pkg:github/libexpat/libexpat",
                    "defaultStatus": "unaffected",
                    "versions": [
                        {
                            "version": "0",
                            "status": "affected",
                            "versionType": "semver",
                            "lessThanOrEqual": "2.9.0"
                        }
                    ],
                    "repo": "https://github.com/libexpat/libexpat"
                }