MediumCVE-2026-91858

    Apache Camel: Improper Restriction of XML External Entity Reference (CVE-2026-91858)

    Published Last modified Sources: BSI, CVE.org

    What is affected, what to do

    FopProducer transforms the incoming XSL-FO message body by creating a javax.xml.transform.TransformerFactory through TransformerFactory.newInstance() and enabling only FEATURE_SECURE_PROCESSING before running an identity transform over the body. On the JDK's built-in transformer, that feature alone already empties the accessExternalDTD and accessExternalStylesheet limits, so an external DTD or entity is refused.

    Update Apache Camel to version 4.18.5, Apache Camel to version 4.22.1.

    Affected
    • Apache Camel lt 4.0.0..4.18.5
    • Apache Camel lt 4.19.0..4.22.1
    Fixed in
    • Apache Camel 4.18.5
    • Apache Camel 4.22.1

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    6.5

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: Vendor (CNA), CVSS v3

    6.5

    CVSS v3

    Severity Medium on the scale from 0 to 10.

    Source: BSI, CVE.org

    0.3 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 23.3

    Show all metrics
    Severity
    Medium
    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
    66.80 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
    6.5 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
    6.5
    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
    0.3 %
    Low — model estimates < 1% 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
    23.3
    Elevated — this CVE ranks above at least 10% of all CVEs scored today.
    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
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-611

    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
    Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
    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

    FopProducer transforms the incoming XSL-FO message body by creating a javax.xml.transform.TransformerFactory through TransformerFactory.newInstance() and enabling only FEATURE_SECURE_PROCESSING before running an identity transform over the body. On the JDK's built-in transformer, that feature alone already empties the accessExternalDTD and accessExternalStylesheet limits, so an external DTD or entity is refused. When a third-party JAXP TransformerFactory such as Saxon-HE is on the classpath, for example because the application also uses camel-xslt-saxon or camel-saxon, TransformerFactory.newInstance() returns that implementation instead, and FEATURE_SECURE_PROCESSING on its own does not restrict external resource access on it. A DOCTYPE with an external subset, or an external general entity, declared in the XSL-FO document is then resolved and expanded while the body is transformed. An external sender whose XSL-FO reaches a fop producer could therefore read files readable by the Camel process and cause the process to issue requests to hosts the document names. camel-fop does not bring such a factory itself, and excludes Xalan, so a default deployment using the JDK transformer is not affected; the issue is reachable only where another component has placed an alternative JAXP TransformerFactory on the classpath. Releases on the 4.14.x line and earlier reached end of life before this issue was resolved and do not receive a fix.

    Source: BSI WID Portal, BSI CSAF, cvelistv5, NVD (NIST), CVE.org (MITRE)

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    Apache Software FoundationApache Camel
    • 4.19.0 – < 4.22.1
    • 4.0.0 – < 4.18.5
    • 4.22.1
    • 4.18.5
    ApacheCamel
    • < 4.23.0
    • < 4.18.5
    • < 4.22.1
    • 4.23.0
    • 4.18.5
    • 4.22.1

    Vendors and products

    Weakness classes (CWE)

    • CWE-611Improper Restriction of XML External Entity Reference

      Base

      The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.

      Entry at MITRE CWE-611

    References & sources

    • camel.apache.orgApache Camel Security Advisory - CVE-2026-91858Vendor advisory
    • issues.apache.orgCAMEL-24605Issue tracking
    • github.comFix on main, released in 4.23.0 (commit 209c67a851d3c145583d25829b7ffac0c500674b)Patch
    • github.comBackport to camel-4.22.x, released in 4.22.1 (commit f689a9c92f0e6c406f9a0256c7d940024cf56782)Patch
    • github.comBackport to camel-4.18.x, released in 4.18.5 (commit 9c06c6d265d70be30023e7514456b697e91db69e)Patch

    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).

    1. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: none known, automatable: no

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      SSVC assessmentadded
      —
      {"id":"CVE-2026-91858","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-10-19T14:29:43.649018Z"}

      Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

    2. ReceivedApache

      CVSS V3.1: AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N

      Weakness type: CWE-611

      Description added or changed

      Show 9 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      FopProducer transforms the incoming XSL-FO message body by creating a javax.xml.transform.TransformerFactory through TransformerFactory.newInstance() and enabling only FEATURE_SECURE_PROCESSING before running an identity transform over the body. On the JDK's built-in transformer, that feature alone already empties the accessExternalDTD and accessExternalStylesheet limits, so an external DTD or entity is refused. When a third-party JAXP TransformerFactory such as Saxon-HE is on the classpath, for example because the application also uses camel-xslt-saxon or camel-saxon, TransformerFactory.newInstance() returns that implementation instead, and FEATURE_SECURE_PROCESSING on its own does not restrict external resource access on it. A DOCTYPE with an external subset, or an external general entity, declared in the XSL-FO document is then resolved and expanded while the body is transformed. An external sender whose XSL-FO reaches a fop producer could therefore read files readable by the Camel process and cause the process to issue requests to hosts the document names. camel-fop does not bring such a factory itself, and excludes Xalan, so a default deployment using the JDK transformer is not affected; the issue is reachable only where another component has placed an alternative JAXP TransformerFactory on the classpath. Releases on the 4.14.x line and earlier reached end of life before this issue was resolved and do not receive a fix.
      CVSSadded
      —
      AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N
      Weakness type (CWE)added
      —
      CWE-611
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/91xxx/CVE-2026-91858.json">CVE-2026-91858</a>
      Referenceadded
      —
      https://camel.apache.org/security/CVE-2026-91858.html
      Referenceadded
      —
      https://github.com/apache/camel/pull/26108
      Referenceadded
      —
      https://github.com/apache/camel/pull/26168
      Referenceadded
      —
      https://github.com/apache/camel/pull/26169
      Referenceadded
      —
      https://issues.apache.org/jira/browse/CAMEL-24605

      Source identifier: security@apache.org

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