CVE-2022-40674· NVD / CVE Program· CNA mitre

libexpat before 2.4.9 has a use-after-free in the doContent function in xmlparse.c.

Noroxi assessment

Priority: Monitor (action score 33/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 2.2% (FIRST EPSS); higher than 82.8% of all records.
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
Fixed version: expat (AlmaLinux:8) 2.2.5-8.el8_6.3; expat-devel (AlmaLinux:8) 2.2.5-8.el8_6.3; firefox (AlmaLinux:8) 102.3.0-7.el8_6.alma.
Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to expat (AlmaLinux:8) 2.2.5-8.el8_6.3; expat-devel (AlmaLinux:8) 2.2.5-8.el8_6.3; firefox (AlmaLinux:8) 102.3.0-7.el8_6.alma or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

HighCVSS 8.1 · v3.1—No exploit Fix available

Published: Sep 14, 2022
Updated: Oct 14, 2026
EPSS: 2.2% · 82th percentile
CWE: CWE-416

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 32 / 40 · 8.1 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 1 / 30 · 2.2%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: 8.1
CNA · mitre: 8.1; agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
libexpat project	libexpat	cpe:2.3:a:libexpat_project:libexpat
debian	debian linux	cpe:2.3:o:debian:debian_linux
fedoraproject	fedora	cpe:2.3:o:fedoraproject:fedora

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

debian debian linux10.0
debian debian linux11.0
fedoraproject fedora35
fedoraproject fedora36
fedoraproject fedora37
libexpat project libexpatbefore 2.4.9

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
AlmaLinux:8	expat	before 2.2.5-8.el8_6.3	2.2.5-8.el8_6.3
AlmaLinux:8	expat-devel	before 2.2.5-8.el8_6.3	2.2.5-8.el8_6.3
AlmaLinux:8	firefox	before 102.3.0-7.el8_6.alma	102.3.0-7.el8_6.alma
AlmaLinux:8	mingw32-expat	before 2.4.8-2.el8	2.4.8-2.el8
AlmaLinux:8	mingw64-expat	before 2.4.8-2.el8	2.4.8-2.el8
AlmaLinux:8	thunderbird	before 102.3.0-4.el8_6.alma	102.3.0-4.el8_6.alma
AlmaLinux:9	expat	before 2.2.10-12.el9_0.3	2.2.10-12.el9_0.3
AlmaLinux:9	expat-devel	before 2.2.10-12.el9_0.3	2.2.10-12.el9_0.3
AlmaLinux:9	firefox	before 102.3.0-7.el9_0.alma	102.3.0-7.el9_0.alma
AlmaLinux:9	thunderbird	before 102.3.0-4.el9_0.alma.plus	102.3.0-4.el9_0.alma.plus
Alpine:v3.13	expat	before 2.2.10-r7	2.2.10-r7
Alpine:v3.14	expat	before 2.4.9-r0	2.4.9-r0
Debian:10	expat	before 2.2.6-2+deb10u5	2.2.6-2+deb10u5
Debian:11	expat	before 2.2.10-2+deb11u4	2.2.10-2+deb11u4
Debian:12	expat	before 2.4.8-2	2.4.8-2
Debian:12	libxmltok	from 0	—
openSUSE:Leap 15.4	expat	before 2.4.4-150400.3.9.1	2.4.4-150400.3.9.1
openSUSE:Leap Micro 5.2	expat	before 2.2.5-150000.3.22.1	2.2.5-150000.3.22.1
openSUSE:Tumbleweed	expat	before 2.4.9-1.1	2.4.9-1.1
openSUSE:Tumbleweed	MozillaFirefox	before 107.0-1.1	107.0-1.1
Red Hat:enterprise_linux:7::client	expat	before 0:2.1.0-15.el7_9	0:2.1.0-15.el7_9
Red Hat:enterprise_linux:7::client	expat-debuginfo	before 0:2.1.0-15.el7_9	0:2.1.0-15.el7_9
Red Hat:enterprise_linux:7::client	expat-devel	before 0:2.1.0-15.el7_9	0:2.1.0-15.el7_9
Red Hat:enterprise_linux:7::client	expat-static	before 0:2.1.0-15.el7_9	0:2.1.0-15.el7_9

+74

Same product

libexpat project: all records

Other highest-scoring records for the same primary product.

CVE-2022-25236xmlparse.c in Expat (aka libexpat) before 2.4.5 allows attackers to insert namespace-separator characters into namespace URIs.
50Plan
CVE-2022-23852Expat (aka libexpat) before 2.4.4 has a signed integer overflow in XML_GetBuffer, for configurations with a nonzero XML_CONTEXT_BYTES.
41Plan
CVE-2022-22822addBinding in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.
41Plan

Published before and after this one in the same product

← EarlierCVE-2022-25314Feb 18, 2022 · In Expat (aka libexpat) before 2.4.5, there is an integer overflow in copyString.
31Monitor
← EarlierCVE-2022-25315Feb 18, 2022 · In Expat (aka libexpat) before 2.4.5, there is an integer overflow in storeRawNames.
40Plan
Later →CVE-2022-43680Oct 24, 2022 · In libexpat through 2.4.9, there is a use-after free caused by overeager destruction of a shared DTD in XML_ExternalEntityParserCreate in ou
31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
almalinux:expat	2.2.10-12.el9_0.3 · AlmaLinux:9	Package registry (OSV)
almalinux:expat-devel	2.2.10-12.el9_0.3 · AlmaLinux:9	Package registry (OSV)
almalinux:firefox	102.3.0-7.el9_0.alma · AlmaLinux:9	Package registry (OSV)
almalinux:mingw32-expat	2.4.8-2.el8 · AlmaLinux:8	Package registry (OSV)
almalinux:mingw64-expat	2.4.8-2.el8 · AlmaLinux:8	Package registry (OSV)
almalinux:thunderbird	102.3.0-4.el8_6.alma · AlmaLinux:8	Package registry (OSV)
alpine:expat	2.2.10-r7 · Alpine:v3.13	Package registry (OSV)
debian:expat	2.4.8-2 · Debian:12	Package registry (OSV)
opensuse:expat	2.4.4-150400.3.9.1 · openSUSE:Leap 15.4	Package registry (OSV)
opensuse:MozillaFirefox	107.0-1.1 · openSUSE:Tumbleweed	Package registry (OSV)
red hat:compat-expat1	0:1.95.8-9.el6_10 · Red Hat:rhel_els:6	Package registry (OSV)
red hat:compat-expat1-debuginfo	0:1.95.8-9.el6_10 · Red Hat:rhel_els:6	Package registry (OSV)
red hat:expat	0:2.2.5-4.el8_4.4 · Red Hat:rhel_eus:8.4::baseos	Package registry (OSV)
red hat:expat-debuginfo	0:2.2.5-4.el8_4.4 · Red Hat:rhel_eus:8.4::baseos	Package registry (OSV)
red hat:expat-debugsource	0:2.2.5-4.el8_4.4 · Red Hat:rhel_eus:8.4::baseos	Package registry (OSV)
red hat:expat-devel	0:2.2.5-4.el8_4.4 · Red Hat:rhel_eus:8.4::baseos	Package registry (OSV)
red hat:expat-static	0:2.1.0-15.el7_9 · Red Hat:enterprise_linux:7::client	Package registry (OSV)
red hat:firefox	0:102.3.0-7.el7_9 · Red Hat:enterprise_linux:7::client	Package registry (OSV)
red hat:firefox-debuginfo	0:102.3.0-7.el7_9 · Red Hat:enterprise_linux:7::client	Package registry (OSV)
red hat:thunderbird	0:102.3.0-4.el8_4 · Red Hat:rhel_eus:8.4::appstream	Package registry (OSV)
red hat:thunderbird-debuginfo	0:102.3.0-4.el8_4 · Red Hat:rhel_eus:8.4::appstream	Package registry (OSV)
red hat:thunderbird-debugsource	0:102.3.0-4.el8_4 · Red Hat:rhel_eus:8.4::appstream	Package registry (OSV)
rocky linux:expat	0:2.2.10-12.el9_0.3 · Rocky Linux:9	Package registry (OSV)
rocky linux:firefox	0:102.3.0-7.el8_6 · Rocky Linux:8	Package registry (OSV)
rocky linux:mingw-expat	0:2.4.8-2.el8 · Rocky Linux:8	Package registry (OSV)
rocky linux:thunderbird	0:102.3.0-4.el8_6 · Rocky Linux:8	Package registry (OSV)
suse:expat	2.1.0-21.25.1 · SUSE:OpenStack Cloud 9	Package registry (OSV)
suse:expat	2.4.4-150400.3.9.1 · SUSE:Linux Enterprise Micro 5.3	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days+1% in 7 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

TR-22-0653 · Oct 3, 2022(Python için Güvenlik Güncellemeleri)

All national notices →

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
No account or password is required.
No user action is required.
Special conditions such as timing or configuration are required.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Attack vector: Network
Attack complexity: High
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1free(dev->buf);
2/* ... another thread is still running ... */
3process(dev->buf);

Fixed

1lock(&dev->lock);
2free(dev->buf);
3dev->buf = NULL;
4unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

Fix✗ → ✓Sep 28, 2026, 10:46 PM UTC

For records you follow, these changes also arrive as notifications. →

References

github.com/libexpat/libexpat/pull/629

Show all references (14 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records