CVE-2026-93990

EUVD-2026-83618
Expat before 2.8.5 fails to validate that a high surrogate in UTF-16 input is followed by a low surrogate, allowing malformed UTF-16 sequences to be accepted. Attackers can supply UTF-16 encoded XML containing lone high surrogates that consume the following code unit, causing Expat to pass unpaired surrogates to applications built with XML_UNICODE and to silently replace input characters in other builds.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
VulnCheckCNA
7.5 HIGH
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 34.75%
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources (CNA/ADP records, vendor advisories, Enginsight analysis).
VendorProductVersionSource
libexpat_projectlibexpat
𝑥
< 2.8.5
CNA
Debian logo
Debian Releases
Debian Product
Codename
expat
bookworm
vulnerable
bookworm (security)
2.5.0-1+deb12u5
fixed
forky
2.9.0-1
fixed
sid
2.9.0-1
fixed
trixie
vulnerable
trixie (security)
2.9.0-1~deb13u1
fixed
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
expat
bionic
needs-triage
focal
needs-triage
jammy
needs-triage
noble
needs-triage
resolute
needs-triage
stonking
needs-triage
trusty
needs-triage
xenial
needs-triage
apache2
bionic
not-affected
focal
not-affected
jammy
not-affected
noble
not-affected
resolute
not-affected
stonking
not-affected
trusty
not-affected
xenial
not-affected
apr-util
bionic
not-affected
focal
not-affected
jammy
not-affected
noble
not-affected
resolute
not-affected
stonking
not-affected
trusty
not-affected
xenial
not-affected
cmake
bionic
not-affected
focal
not-affected
jammy
not-affected
noble
not-affected
resolute
not-affected
stonking
not-affected
xenial
not-affected
ghostscript
bionic
not-affected
focal
not-affected
jammy
not-affected
noble
not-affected
resolute
not-affected
stonking
not-affected
xenial
not-affected
texlive-bin
bionic
not-affected
focal
not-affected
jammy
not-affected
noble
not-affected
resolute
not-affected
stonking
not-affected
xenial
not-affected
xmlrpc-c
bionic
needs-triage
focal
needs-triage
jammy
needs-triage
noble
needs-triage
resolute
needs-triage
stonking
needs-triage
trusty
needs-triage
xenial
needs-triage
vnc4
bionic
needs-triage
jammy
dne
noble
dne
resolute
dne
stonking
dne
trusty
needs-triage
xenial
needs-triage
wbxml2
bionic
needs-triage
focal
needs-triage
jammy
needs-triage
noble
needs-triage
resolute
needs-triage
stonking
needs-triage
xenial
needs-triage
swish-e
bionic
needs-triage
focal
needs-triage
jammy
needs-triage
noble
needs-triage
resolute
needs-triage
stonking
needs-triage
xenial
needs-triage
insighttoolkit4
bionic
needs-triage
focal
needs-triage
jammy
needs-triage
noble
dne
resolute
dne
stonking
dne
xenial
needs-triage
cadaver
bionic
needs-triage
focal
needs-triage
jammy
needs-triage
noble
needs-triage
resolute
needs-triage
stonking
needs-triage
xenial
needs-triage
gdcm
bionic
needs-triage
focal
not-affected
jammy
not-affected
noble
not-affected
resolute
not-affected
stonking
not-affected
trusty
not-affected
xenial
needs-triage
ayttm
jammy
dne
noble
dne
resolute
dne
stonking
dne
xenial
needs-triage
cableswig
jammy
dne
noble
dne
resolute
dne
stonking
dne
xenial
needs-triage
coin3
bionic
needs-triage
focal
not-affected
jammy
not-affected
noble
not-affected
resolute
not-affected
stonking
not-affected
trusty
needs-triage
xenial
needs-triage
matanza
bionic
needs-triage
focal
ignored
jammy
ignored
noble
ignored
resolute
ignored
stonking
ignored
xenial
needs-triage
tdom
bionic
needs-triage
focal
needs-triage
jammy
needs-triage
noble
needs-triage
resolute
needs-triage
stonking
needs-triage
xenial
needs-triage
vtk
jammy
dne
noble
dne
resolute
dne
stonking
dne
trusty
needs-triage
xenial
needs-triage
smart
bionic
needs-triage
jammy
dne
noble
dne
resolute
dne
stonking
dne
xenial
needs-triage
firefox
jammy
not-affected
noble
not-affected
resolute
not-affected
stonking
not-affected
thunderbird
jammy
not-affected
noble
not-affected
resolute
not-affected
stonking
not-affected
libxmltok
bionic
needs-triage
focal
needs-triage
jammy
needs-triage
noble
needs-triage
resolute
dne
stonking
dne
xenial
needs-triage
openSUSE logo
openSUSE / SLES Releases
openSUSE Product
Release
MozillaFirefox
suse enterprise desktop 15 SP7
153.5.0-150400.157.16.1
fixed
suse enterprise sap 12 SP5
153.5.0-118.16.2
fixed
suse enterprise sap 15 SP4
153.5.0-150400.157.16.1
fixed
suse enterprise sap 15 SP5
153.5.0-150400.157.16.1
fixed
suse enterprise sap 15 SP6
153.5.0-150400.157.16.1
fixed
suse enterprise sap 15 SP7
153.5.0-150400.157.16.1
fixed
suse enterprise server 12 SP5
153.5.0-118.16.2
fixed
suse enterprise server 15 SP4
153.5.0-150400.157.16.1
fixed
suse enterprise server 15 SP5
153.5.0-150400.157.16.1
fixed
suse enterprise server 15 SP6
153.5.0-150400.157.16.1
fixed
suse enterprise server 15 SP7
153.5.0-150400.157.16.1
fixed
MozillaFirefox-devel
suse enterprise desktop 15 SP7
153.5.0-150400.157.16.1
fixed
suse enterprise sap 12 SP5
153.5.0-118.16.2
fixed
suse enterprise sap 15 SP4
153.5.0-150400.157.16.1
fixed
suse enterprise sap 15 SP5
153.5.0-150400.157.16.1
fixed
suse enterprise sap 15 SP6
153.5.0-150400.157.16.1
fixed
suse enterprise sap 15 SP7
153.5.0-150400.157.16.1
fixed
suse enterprise server 12 SP5
153.5.0-118.16.2
fixed
suse enterprise server 15 SP4
153.5.0-150400.157.16.1
fixed
suse enterprise server 15 SP5
153.5.0-150400.157.16.1
fixed
suse enterprise server 15 SP6
153.5.0-150400.157.16.1
fixed
suse enterprise server 15 SP7
153.5.0-150400.157.16.1
fixed
MozillaFirefox-translations-common
suse enterprise desktop 15 SP7
153.5.0-150400.157.16.1
fixed
suse enterprise sap 12 SP5
153.5.0-118.16.2
fixed
suse enterprise sap 15 SP4
153.5.0-150400.157.16.1
fixed
suse enterprise sap 15 SP5
153.5.0-150400.157.16.1
fixed
suse enterprise sap 15 SP6
153.5.0-150400.157.16.1
fixed
suse enterprise sap 15 SP7
153.5.0-150400.157.16.1
fixed
suse enterprise server 12 SP5
153.5.0-118.16.2
fixed
suse enterprise server 15 SP4
153.5.0-150400.157.16.1
fixed
suse enterprise server 15 SP5
153.5.0-150400.157.16.1
fixed
suse enterprise server 15 SP6
153.5.0-150400.157.16.1
fixed
suse enterprise server 15 SP7
153.5.0-150400.157.16.1
fixed
MozillaFirefox-translations-other
suse enterprise desktop 15 SP7
153.5.0-150400.157.16.1
fixed
suse enterprise sap 15 SP4
153.5.0-150400.157.16.1
fixed
suse enterprise sap 15 SP5
153.5.0-150400.157.16.1
fixed
suse enterprise sap 15 SP6
153.5.0-150400.157.16.1
fixed
suse enterprise sap 15 SP7
153.5.0-150400.157.16.1
fixed
suse enterprise server 15 SP4
153.5.0-150400.157.16.1
fixed
suse enterprise server 15 SP5
153.5.0-150400.157.16.1
fixed
suse enterprise server 15 SP6
153.5.0-150400.157.16.1
fixed
suse enterprise server 15 SP7
153.5.0-150400.157.16.1
fixed
MozillaThunderbird
suse enterprise desktop 15 SP7
153.5.0-150400.13.9.1
fixed
suse enterprise sap 15 SP7
153.5.0-150400.13.9.1
fixed
suse enterprise server 15 SP7
153.5.0-150400.13.9.1
fixed
suse enterprise workstation 15 SP7
153.5.0-150400.13.9.1
fixed
MozillaThunderbird-translations-common
suse enterprise desktop 15 SP7
153.5.0-150400.13.9.1
fixed
suse enterprise sap 15 SP7
153.5.0-150400.13.9.1
fixed
suse enterprise server 15 SP7
153.5.0-150400.13.9.1
fixed
suse enterprise workstation 15 SP7
153.5.0-150400.13.9.1
fixed
MozillaThunderbird-translations-other
suse enterprise desktop 15 SP7
153.5.0-150400.13.9.1
fixed
suse enterprise sap 15 SP7
153.5.0-150400.13.9.1
fixed
suse enterprise server 15 SP7
153.5.0-150400.13.9.1
fixed
suse enterprise workstation 15 SP7
153.5.0-150400.13.9.1
fixed
expat
suse enterprise desktop 15 SP7
2.8.5-150700.3.15.1
fixed
suse enterprise sap 12 SP5
2.8.5-21.55.1
fixed
suse enterprise sap 15 SP4
2.8.5-150400.3.40.1
fixed
suse enterprise sap 15 SP5
2.8.5-150400.3.40.1
fixed
suse enterprise sap 15 SP6
2.8.5-150400.3.40.1
fixed
suse enterprise sap 15 SP7
2.8.5-150700.3.15.1
fixed
suse enterprise server 12 SP3
2.8.5-21.55.1
fixed
suse enterprise server 12 SP5
2.8.5-21.55.1
fixed
suse enterprise server 15 SP4
2.8.5-150400.3.40.1
fixed
suse enterprise server 15 SP5
2.8.5-150400.3.40.1
fixed
suse enterprise server 15 SP6
2.8.5-150400.3.40.1
fixed
suse enterprise server 15 SP7
2.8.5-150700.3.15.1
fixed
libexpat-devel
suse enterprise desktop 15 SP7
2.8.5-150700.3.15.1
fixed
suse enterprise sap 12 SP5
2.8.5-21.55.1
fixed
suse enterprise sap 15 SP4
2.8.5-150400.3.40.1
fixed
suse enterprise sap 15 SP5
2.8.5-150400.3.40.1
fixed
suse enterprise sap 15 SP6
2.8.5-150400.3.40.1
fixed
suse enterprise sap 15 SP7
2.8.5-150700.3.15.1
fixed
suse enterprise server 12 SP5
2.8.5-21.55.1
fixed
suse enterprise server 15 SP4
2.8.5-150400.3.40.1
fixed
suse enterprise server 15 SP5
2.8.5-150400.3.40.1
fixed
suse enterprise server 15 SP6
2.8.5-150400.3.40.1
fixed
suse enterprise server 15 SP7
2.8.5-150700.3.15.1
fixed
libexpat1
suse enterprise desktop 15 SP7
2.8.5-150700.3.15.1
fixed
suse enterprise sap 12 SP5
2.8.5-21.55.1
fixed
suse enterprise sap 15 SP4
2.8.5-150400.3.40.1
fixed
suse enterprise sap 15 SP5
2.8.5-150400.3.40.1
fixed
suse enterprise sap 15 SP6
2.8.5-150400.3.40.1
fixed
suse enterprise sap 15 SP7
2.8.5-150700.3.15.1
fixed
suse enterprise server 12 SP3
2.8.5-21.55.1
fixed
suse enterprise server 12 SP5
2.8.5-21.55.1
fixed
suse enterprise server 15 SP4
2.8.5-150400.3.40.1
fixed
suse enterprise server 15 SP5
2.8.5-150400.3.40.1
fixed
suse enterprise server 15 SP6
2.8.5-150400.3.40.1
fixed
suse enterprise server 15 SP7
2.8.5-150700.3.15.1
fixed
libexpat1-32bit
suse enterprise desktop 15 SP7
2.8.5-150700.3.15.1
fixed
suse enterprise sap 12 SP5
2.8.5-21.55.1
fixed
suse enterprise sap 15 SP4
2.8.5-150400.3.40.1
fixed
suse enterprise sap 15 SP5
2.8.5-150400.3.40.1
fixed
suse enterprise sap 15 SP6
2.8.5-150400.3.40.1
fixed
suse enterprise sap 15 SP7
2.8.5-150700.3.15.1
fixed
suse enterprise server 12 SP3
2.8.5-21.55.1
fixed
suse enterprise server 12 SP5
2.8.5-21.55.1
fixed
suse enterprise server 15 SP4
2.8.5-150400.3.40.1
fixed
suse enterprise server 15 SP5
2.8.5-150400.3.40.1
fixed
suse enterprise server 15 SP6
2.8.5-150400.3.40.1
fixed
suse enterprise server 15 SP7
2.8.5-150700.3.15.1
fixed
Red Hat logo
Red Hat Enterprise Linux Releases
Red Hat Product
Release
expat
RHEL 8
0:2.5.0-4.el8_10
fixed
RHEL 9
0:2.5.0-6.el9_8.5
fixed
expat-devel
RHEL 8
0:2.5.0-4.el8_10
fixed
RHEL 9
0:2.5.0-6.el9_8.5
fixed
Amazon Linux logo
Amazon Linux Releases
Amazon Package
Release
firefox
Amazon Linux 2023
0:140.17.0-1.amzn2023.0.1
fixed
firefox-debuginfo
Amazon Linux 2023
0:140.17.0-1.amzn2023.0.1
fixed
firefox-debugsource
Amazon Linux 2023
0:140.17.0-1.amzn2023.0.1
fixed
thunderbird
Amazon Linux 2
0:153.5.1-1.amzn2.0.1
fixed
Azure Linux logo
Azure Linux Releases
Azure Package
Release
expat
Azure Linux 3.0
0:2.8.5-1.azl3
fixed
Common Weakness Enumeration
Vulnerability Media Exposure
References
https://blog.hartwork.org/posts/expat-2-8-5-released/
https://github.com/libexpat/libexpat
https://github.com/libexpat/libexpat/commit/ff6e1d7e750bbe245178f51a47a965dc8342861a
https://github.com/libexpat/libexpat/pull/1282
https://github.com/libexpat/libexpat/releases/tag/R_2_8_5
https://www.vulncheck.com/advisories/expat-through-2.8.4-malformed-utf-16-acceptance-via-unchecked-surrogate