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Full vulnerability report · 2026
CVE-2026-32777High confidence

libexpat before 2.7.5 allows an infinite loop while parsing DTD content

libexpat project · libexpat

Official source article: Siemens SSA-082556 ↗. Check the applicable product and release in the original source.

4.0MediumCVSS 3.1
Recommended action
Patch only the product branches with a verified fix

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 26 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:Medium, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • EPSS is 0.17% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict local access and enforce least privilege on affected hosts.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs libexpat project libexpat and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: As exposure requiresRemediation target: Within 365 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 26 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Distribution package intelligence

Release-specific package status

Alpine, Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

15 package states
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Distribution releaseSource packageVendor stateFixed versionEvidence
Alpine v3.23v3.23 · mainexpatVendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected.2.7.5-r0Alpine Security Database ↗Source updated 3 Oct 2026
Alpine v3.22v3.22 · mainexpatVendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected.2.7.5-r0Alpine Security Database ↗Source updated 3 Oct 2026
Alpine v3.21v3.21 · mainexpatVendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected.2.7.5-r0Alpine Security Database ↗Source updated 3 Oct 2026
Debian trixietrixie · sourceexpatVendor fix publishedDebian records a fixed source-package version for this release.2.8.2-1~deb13u1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian bookwormbookworm · sourceexpatVendor fix publishedDebian records a fixed source-package version for this release.2.5.0-1+deb12u4Debian Security Tracker ↗Source updated 5 Oct 2026
Debian forkyforky · sourceexpatVendor fix publishedDebian records a fixed source-package version for this release.2.7.5-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian sidsid · sourceexpatVendor fix publishedDebian records a fixed source-package version for this release.2.7.5-1Debian Security Tracker ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · esm-appslibxmltokUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · esm-appsswish-eUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · esm-appsxmlrpc-cUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivecadaverUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archiveexpatVendor fix publishedCanonical reports that a fixed source package version has been published. Repository candidate availability is not checked by BlackTree.2.6.1-2ubuntu0.5Canonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivematanzaUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivetdomUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivewbxml2Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

2 current
CVE-2026-32777 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitylibexpat: libexpat: Denial of Service via infinite loop in DTD content parsing
21 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • expat as a component of Red Hat Enterprise Linux 10
  • expat-devel as a component of Red Hat Enterprise Linux 10
  • expat.src as a component of Red Hat Enterprise Linux 10
  • compat-expat1 as a component of Red Hat Enterprise Linux 6
  • compat-expat1.src as a component of Red Hat Enterprise Linux 6
  • expat as a component of Red Hat Enterprise Linux 6
  • expat-devel as a component of Red Hat Enterprise Linux 6
  • expat.src as a component of Red Hat Enterprise Linux 6
  • expat as a component of Red Hat Enterprise Linux 7
  • expat-devel as a component of Red Hat Enterprise Linux 7
  • expat-static as a component of Red Hat Enterprise Linux 7
  • expat.src as a component of Red Hat Enterprise Linux 7
Summary
A flaw was found in libexpat. A remote attacker could exploit this vulnerability by providing specially crafted Document Type Definition (DTD) content. This could lead to an infinite loop during parsing, resulting in a Denial of Service (DoS) for the application using libexpat.
Remediation
Fix deferred
SSA-082556 · CSAF 2.0 · revision 7 · interimSiemens ProductCERTSSA-082556: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.5
5 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= V3.1.5 < V3.1.6
  • SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= V3.1.5 < V3.1.6
  • SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= V3.1.5 < V3.1.6
  • SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= V3.1.5 < V3.1.6
  • SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= V3.1.5 < V3.1.6
Summary
libexpat before 2.7.5 allows an infinite loop while parsing DTD content.
Remediation
Update to V3.1.6 or later version
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-12349

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionPatch only the product branches with a verified fix

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 26 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

libexpat before 2.7.5 allows an infinite loop while parsing DTD content.

What

libexpat before 2.7.5 allows an infinite loop while parsing DTD content.

Why

A malformed condition prevents a loop from making progress or terminating, allowing resource exhaustion.

How

An attacker operating through local access may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

libexpat before 2.7.5 allows an infinite loop while parsing DTD content.

Why

A malformed condition prevents a loop from making progress or terminating, allowing resource exhaustion.

How

An attacker operating through local access may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
local access → Loop with Unreachable Exit Condition ('Infinite Loop') → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Local
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-835 ↗

CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop'). The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.ALowAvailability impact: A successful attack can cause a limited loss.
Post-exploitation / living off the land
The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
UnauthenticatedCWE-835Public exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-2026-2912Dell PowerScale OneFS: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Dell PowerScale OneFS ausnutzen, um beliebigen Programmcode auszuführen, um einen Denial of Service Angriff durchzuführen, um Informationen offenzulegen, und um Daten zu manipulieren.

Official advisory ↗
BSI · German · WID-SEC-2026-2355Dell integrated Dell Remote Access Controller: Mehrere Schwachstellen

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Dell integrated Dell Remote Access Controller ausnutzen, um einen Denial-of-Service auszulösen, Informationen offenzulegen, Sicherheitsmaßnahmen zu umgehen und potentiell Code auszuführen.

Official advisory ↗
BSI · German · WID-SEC-2026-2189Dell PowerProtect Data Domain: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Dell PowerProtect Data Domain ausnutzen, um seine Privilegien zu erhöhen um beliebigen Programmcode auszuführen, um Sicherheitsvorkehrungen zu umgehen, um einen Denial of Service Angriff durchzuführen, um einen Cross-Site Scripting Angriff durchzuführen, um Informationen offenzulegen, und um Dateien zu manipulieren.

Official advisory ↗
BSI · German · WID-SEC-2026-0733libexpat: Mehrere Schwachstellen ermöglichen Denial of Service

Ein lokaler Angreifer kann mehrere Schwachstellen in libexpat ausnutzen, um einen Denial of Service Angriff durchzuführen.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0627Multiples vulnérabilités dans les produits Splunk

d?id=CVE-2026-31790 Référence CVE CVE-2026-32141 https://www.cve.org/CVERecord?id=CVE-2026-32141 Référence CVE CVE-2026-32280 https://www.cve.org/CVERecord?id=CVE-2026-32280 Référence CVE CVE-2026-32281 https://www.cve.org/CVERecord?id=CVE-2026-32281 Référence CVE CVE-2026-32282 https://www.cve.org/CVERecord?id=CVE-2026-32282 Référence CVE CVE-2026-32283 https://www.cve.org/CVERecord?id=CVE-2026-32283 Référence CVE CVE-2026-32288 https://www.cve.org/CVERecord?id=CVE-2026-32288 Référence CVE CVE-2026-32289 https://www.cve.org/CVERecord?id=CVE-2026-32289 Référence CVE CVE-2026-32776 https://www.cve.org/CVERecord?id=CVE-2026-32776 Référence CVE CVE-2026-32777 https://www.cve.org/CVERecord?id=CVE-2026-32777 Référence CVE CVE-2026-32778 https://www.cve.org/CVERecord?id=CVE-2026-32778 Référence CVE CVE-2026-33055 https://www.cve.org/CVERecord?id=CVE-2026-33055 Référence CVE CVE-2026-33056 https://www.cve.org/CVERecord?id=CVE-2026-33056 Référence CVE CVE-2026-33186 https://www.cve.org/CVERecord?id=CVE-2026-33186 Référence CVE CVE-2026-33228 https://www.cve.org/CVERecord?id=CVE-2026-33228 Référence CVE CVE-2026-33810 https://www.cve.org/CVERecord?id=CVE-2026-33810 Référence CVE CVE-2026-33870 https://www.cve.org/CVERecord?id=CVE-2026-33870 Référence CVE CVE-2026-33871 https://www.cve.org/CVERecord?id=

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-007534libexpat projectのlibexpatにおける無限ループに関する脆弱性

libexpatのバージョン2.7.5より前のものには、DTDコンテンツの解析中に無限ループを引き起こす可能性があります。

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Fix availability varies by product
Affected
Fixed
Update to V3.1.6 or later version
Action
Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 16 Mar 2026 · Last source change 14 Jul 2026, 12:48 UTC · CWE-835 · Loop with Unreachable Exit Condition ('Infinite Loop')

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2026-12349
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    < 2.7.5 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    After
    < 2.7.5 · Fixed: Update to V3.1.6 or later version
    Siemens ProductCERT ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
Fixed release recorded from official guidance
ENISA EUVD · EUVD-2026-12349↗Vendor CSAF · Red Hat Product Security↗Siemens ProductCERT security advisory · Siemens SSA-082556↗CVE authority or vendor reference↗Public exploit reference↗Patch or update reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-32777 · cve.blacktree.nl