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Fencer Intel
high 7.5

CVE-2026-115506 json

libexpat through 2.9.0 Denial of Service via Billion Laughs Detection Delay

published 18d ago modified 7d ago also EUVD-2026-108338

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 39%
public exploits
0
none known

Summary

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.

Patch / fix

  • expat Debian 14 2.10.0-1

debian advisories DEBIAN-CVE-2026-115506

  • expat openSUSE Tumbleweed 2.10.0-1.1

opensuse advisories openSUSE-SU-2026:12396-1

  • expat Alpine 3.24, Alpine 3.23, Alpine 3.22 +1 more 2.10.0-r0

alpine advisories ALPINE-CVE-2026-115506

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2026-115506 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-115506 updated cvss 7.5

expat: expat: Denial of Service via delayed entity amplification detection

  • Red Hat Enterprise Linux 7 firefox, firefox 140.17.0-1.el10_2 Red Hat Enterprise Linux 8 expat, firefox, mingw-expat, thunderbird, mingw32-expat, mingw64-expat, +3 more Red Hat Enterprise Linux 9 expat, firefox, firefox-x11, thunderbird, expat 2.7.3-1.el10_2.5, firefox 140.17.0-1.el10_2, +1 more Red Hat Enterprise Linux 10 expat 2.7.3-1.el10_2.5, firefox 140.17.0-1.el10_2, thunderbird 140.17.0-1.el10_2 Red Hat Hardened Images expat 2.7.3-1.el10_2.5
    affected: workaround, no fix available
  • Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    affected: workaround, no fix available
  • Red Hat Enterprise Linux 6 expat, compat-expat1, expat 2.7.3-1.el10_2.5 Red Hat Enterprise Linux 7 expat, expat 2.7.3-1.el10_2.5 Red Hat Enterprise Linux 8 xmlrpc-c, xmlrpc-c-c++, xmlrpc-c-client, xmlrpc-c-client++
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
17d ago

Exploit prediction

0.45% chance of exploitation in the next 30 days, higher than 39% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/hannob/lololol referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 4.0 8.7 CVSS: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

Affected products

  • libexpat libexpat

Classification

Weakness
  • CWE-776 Improper Restriction of Recursive Entity References in DTDs

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.