High 7.5Published Oct 22, 2026

CVE-2026-115506libexpat through 2.9.0 Denial of Service via Billion Laughs Detection Delay

Updated under an hour ago (Oct 28, 2026, 5:20 AM ET)

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It affects libexpat. Add what you run to find out whether that includes you.

EPSS puts the chance of exploitation in the next 30 days at 0.46%, higher than 39% of scored CVEs.

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Every CVE for libexpat

Exploited in the last 30 days

libexpat through 2.9.0 contains a denial of service vulnerability because billion laughs protection in accountingDiffTolerated() in xmlparse.c detects entity amplification too late. Attackers can supply a moderately sized XML document with a large DTD and nested entity expansions to consume tens of seconds of CPU per parse.

CVSS: 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-776
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): 0.46% (percentile 39)
Assigned by: VulnCheck
NVD analysis: Awaiting Analysis
Record last updated: Oct 23, 2026
First seen by InfoSec Signals: Oct 22, 2026

Affected products

Affected products

libexpat libexpat libexpat:libexpat (from the name)	through 2.9.0	CNA record

References

References

https://github.com/libexpat/libexpat/pull/1433	patch, issue-tracking
https://github.com/libexpat/libexpat/issues/1160	issue-tracking
https://github.com/hannob/lololol	exploit
https://github.com/libexpat/libexpat	product
https://www.vulncheck.com/advisories/libexpat-through-2.9.0-denial-of-service-via-billion-laughs-detection-delay	third-party-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.