libexpat Project libexpat: Integer Overflow (CVE-2022-22823)
Published Last modified Sources: Siemens ProductCERT, Debian, CVE.org, Red Hat
What is affected, what to do
build_model in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.
Update libexpat Project libexpat to version 2.4.3, Tenable Nessus to version 8.15.3, Tenable Nessus to version 10.1.1.
- Affected
- libexpat Project libexpat
lt *..2.4.3 - Tenable Nessus
lt *..8.15.3 - Tenable Nessus
lt 10.0.0..10.1.1 - Debian Linux
eq 10.0..10.0 - Debian Linux
eq 11.0..11.0 - Siemens SINEMA Remote Connect Server
lt *..3.1
- libexpat Project libexpat
- Fixed in
- libexpat Project libexpat
2.4.3 - Tenable Nessus
8.15.3 - Tenable Nessus
10.1.1 - Siemens SINEMA Remote Connect Server
3.1
- libexpat Project libexpat
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Metrics
9.8
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
9.8
CVSS v3
Severity Critical on the scale from 0 to 10.
Source: Siemens ProductCERT, Debian, CVE.org, Red Hat
3.6 %
EPSS score
Moderate — model estimates 1-10% exploitation likelihood.
Source: FIRST EPSS, percentile 89.4
Show all metrics
- Severity
- Critical
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 113.21 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 9.8 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 9.8
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 3.6 %
- Moderate — model estimates 1-10% exploitation likelihood.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 89.4
- Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
build_model in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.
Source: siemens_advisory, Debian Security Advisories, cvelistv5, NVD (NIST), redhat_csaf
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| libexpat_project | libexpat |
|
|
| siemens | sinema_remote_connect_server |
|
|
| tenable | nessus |
|
|
Vendors and products
Affected operating systems
| Linux | debian | debian_linux | 10.0 |
| Linux | debian | debian_linux | 11.0 |
| Linux | debian | expat | bullseye |
| Linux | debian | expat | buster |
References & sources
- github.comlibexpat/libexpat/pull/539x_refsource_MISC
- openwall.com[oss-security] 20220117 Expat 2.4.3 released, includes 8 security fixesMailing list, x_refsource_MLIST
- tenable.comsecurity/tns-2022-05x_refsource_CONFIRM
- debian.orgDSA-5073Vendor advisory, x_refsource_DEBIAN
- Siemens ProductCERTproductcert/pdf/ssa-484086.pdfx_refsource_CONFIRM
- security.gentoo.orgGLSA-202209-24Vendor advisory, x_refsource_GENTOO
- Siemens ProductCERTproductcert/html/ssa-484086.html
- Siemens ProductCERTproductcert/html/ssa-398330.html
Changes to this CVE
Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).
Record modifiedSiemens ADP
Show 3 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2022/22xxx/CVE-2022-22823.json">CVE-2022-22823</a>Reference added —https://cert-portal.siemens.com/productcert/html/ssa-398330.htmlReference added —https://cert-portal.siemens.com/productcert/html/ssa-484086.htmlSource identifier: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
Record modifiedMITRE
Show 18 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —http://www.openwall.com/lists/oss-security/2022/01/17/3Reference added —https://cert-portal.siemens.com/productcert/pdf/ssa-484086.pdfReference added —https://github.com/libexpat/libexpat/pull/539Reference added —https://security.gentoo.org/glsa/202209-24Reference added —https://www.debian.org/security/2022/dsa-5073Reference added —https://www.tenable.com/security/tns-2022-05Reference removed http://www.openwall.com/lists/oss-security/2022/01/17/3—Reference removed https://cert-portal.siemens.com/productcert/pdf/ssa-484086.pdf—Reference removed https://github.com/libexpat/libexpat/pull/539—Reference removed https://security.gentoo.org/glsa/202209-24—Reference removed https://www.debian.org/security/2022/dsa-5073—Reference removed https://www.tenable.com/security/tns-2022-05—Reference type removed http://www.openwall.com/lists/oss-security/2022/01/17/3 Types: Mailing List, Third Party Advisory—Reference type removed https://cert-portal.siemens.com/productcert/pdf/ssa-484086.pdf Types: Patch, Third Party Advisory—Reference type removed https://github.com/libexpat/libexpat/pull/539 Types: Third Party Advisory—Reference type removed https://security.gentoo.org/glsa/202209-24 Types: Third Party Advisory—Reference type removed https://www.debian.org/security/2022/dsa-5073 Types: Third Party Advisory—Reference type removed https://www.tenable.com/security/tns-2022-05 Types: Third Party Advisory—Source identifier: cve@mitre.org
Record modifiedCVE Program
Show 18 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —http://www.openwall.com/lists/oss-security/2022/01/17/3Reference added —https://cert-portal.siemens.com/productcert/pdf/ssa-484086.pdfReference added —https://github.com/libexpat/libexpat/pull/539Reference added —https://security.gentoo.org/glsa/202209-24Reference added —https://www.debian.org/security/2022/dsa-5073Reference added —https://www.tenable.com/security/tns-2022-05Reference removed http://www.openwall.com/lists/oss-security/2022/01/17/3—Reference removed https://cert-portal.siemens.com/productcert/pdf/ssa-484086.pdf—Reference removed https://github.com/libexpat/libexpat/pull/539—Reference removed https://security.gentoo.org/glsa/202209-24—Reference removed https://www.debian.org/security/2022/dsa-5073—Reference removed https://www.tenable.com/security/tns-2022-05—Reference type removed http://www.openwall.com/lists/oss-security/2022/01/17/3 Types: Mailing List, Third Party Advisory—Reference type removed https://cert-portal.siemens.com/productcert/pdf/ssa-484086.pdf Types: Patch, Third Party Advisory—Reference type removed https://github.com/libexpat/libexpat/pull/539 Types: Third Party Advisory—Reference type removed https://security.gentoo.org/glsa/202209-24 Types: Third Party Advisory—Reference type removed https://www.debian.org/security/2022/dsa-5073 Types: Third Party Advisory—Reference type removed https://www.tenable.com/security/tns-2022-05 Types: Third Party Advisory—Source identifier: af854a3a-2127-422b-91ae-364da2661108
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<a href="https://intel.neosec.eu/en/cve/CVE-2022-22823"><img src="https://intel.neosec.eu/badge/cve/CVE-2022-22823.svg?lang=en" alt="CVE-2022-22823 – NEOSEC Intel" height="20"></a>