CVE-2026-115506: libexpat through 2.9.0 Denial of Service via Billion Laughs Detection Delay
Vulnerability summary
CVE-2026-115506 is a high (CVSS 8.7) vulnerability in libexpat_project libexpat. EPSS estimates a 0.45% chance of exploitation in the next 30 days, higher than 39% of scored vulnerabilities. 1 public exploit is recorded.
Public exploit (GitHub, Date unknown)
Source freshness unavailable
How is this decided?Timeline
- 22-10-2026PublishedVulnerability first disclosed.
- 23-10-2026Last modifiedVulnerability information updated.
Description
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 metrics
10 scores · 7 sources · 2 versions- NVDNIST8.7HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- OSV · DebianEcosystem advisory · calculated8.7HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- OSV · UbuntuEcosystem advisory · calculated8.7HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- OSV · WolfiEcosystem advisory · calculated8.7HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- OSV · ChainguardEcosystem advisory · calculated8.7HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- OSV · AlpineEcosystem advisory · calculated8.7HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- NVDNIST7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.45%
Chance of exploitation in the next 30 days
Percentile
39%
Versus all other CVEs
30-day change
Change unavailable
Change unavailable
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
1 foundLololol
Maturity: poc
Weaknesses
CWE · root causeAffected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu16 products
- ayttmAll versions (No fix recorded)
- cableswigAll versions (No fix recorded)
- cadaverAll versions (No fix recorded)
- coin3All versions (No fix recorded)
- expatAll versions (No fix recorded)
Chainguard4 products
- expatAll versions (No fix recorded) | < 2.10.0-r0
- expat-devAll versions (No fix recorded) | < 2.10.0-r0
- expat-docAll versions (No fix recorded)
- libexpat1All versions (No fix recorded) | < 2.10.0-r0
Wolfi4 products
- expatAll versions (No fix recorded) | < 2.10.0-r0
- expat-devAll versions (No fix recorded) | < 2.10.0-r0
- expat-docAll versions (No fix recorded)
- libexpat1All versions (No fix recorded) | < 2.10.0-r0
Alpine1 product
- expat< 2.10.0-r0
Debian1 product
- expatAll versions (No fix recorded)
Libexpat1 product
- libexpat≤ 2.9.0
Libexpat_project1 product
- libexpat≤ 2.9.0
7 vendors · 28 products
