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CVE Record

CVE-2026-44990: Apostrophe has default XSS via `xmp` raw-text passthrough in `sanitize-html`

ApostropheCMS is an open-source Node.js content management system, and sanitize-html provides a simple HTML sanitizer with a clear API. Under the default configuration, versions of `sanitize-html` prior to 2.17.4 can turn attacker-controlled content inside a disallowed `xmp` element into live HTML or JavaScript. This is a sanitizer bypass in the default `disallowedTagsMode: 'discard'` path and can lead to stored XSS in applications that render sanitized output back to users. Version 2.17.4 patches the issue.

CriticalCVSS 9.3Not KEV-listedUpdated
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Glexia's TakeAutomated analysiscritical

Security readout for executives and security teams

Plain-English summary

Applications using vulnerable sanitize-html may think they removed unsafe markup, but content inside a blocked xmp tag can become active HTML or JavaScript. If untrusted content is saved and later viewed, this can become stored XSS affecting users who open the content.

Executive priority

Treat as urgent for public-facing CMS, collaboration, support, or profile systems that store user content. The issue can turn a security control into a bypass, enabling browser-side compromise when users view attacker-supplied content.

Technical view

sanitize-html versions before 2.17.4 have a default sanitizer bypass in disallowedTagsMode: discard. Attacker-controlled content inside a disallowed xmp raw-text element can be emitted as live markup or script. The CVE is CWE-79 with CVSS 9.3, network attack vector, low complexity, no privileges, and user interaction required.

Likely exposure

Highest exposure is Node.js or ApostropheCMS-adjacent applications using sanitize-html below 2.17.4 to process user-supplied HTML and render sanitized output. Downstream Red Hat advisories indicate packaged ecosystem tracking, but exact product exposure should be verified from those advisories.

Exploitation context

The provided bundle does not show CISA KEV listing or confirmed active exploitation. Exploitation requires a victim to view rendered sanitized content, but stored XSS can still create serious account, data, and session exposure in the affected origin.

Researcher notes

Focus validation on sanitizer configuration and rendering paths, not only package presence. The reported weakness is in the default discard behavior for disallowed xmp elements. Do not assume exploitability where sanitized output is never rendered to users.

Mitigation direction

  • Upgrade sanitize-html to version 2.17.4 or later.
  • Update lockfiles and redeploy all services bundling vulnerable sanitize-html versions.
  • Check Red Hat advisories if consuming sanitize-html through Red Hat-maintained packages.
  • Review vendor guidance for any additional application-specific mitigations.
  • Prioritize systems accepting rich text, CMS content, comments, or profile HTML.

Validation and detection

  • Inventory direct and transitive sanitize-html package versions.
  • Confirm no deployed artifact contains sanitize-html below 2.17.4.
  • Map where user-controlled HTML is sanitized and later rendered.
  • Review CMS and rich-text workflows for stored content exposure.
  • Track Red Hat CVE and errata status for managed platforms.
Prepared
Confidence
high
Sources
12

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · medium confidence lookup

CWE-79: User-session and phishing behavior lookup

Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-44990 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
Critical
CVSS
9.3 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
2ADP providers
12Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: pocAutomatable: noTechnical Impact: total

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
9.3CVSS 3.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N2.85.8GitHub_M
8.1CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N2.85.2redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

9.3Critical
CVSS 3.1 vector shape for CVE-2026-44990Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPsanitize-html: `sanitize-html`: Stored Cross-Site Scripting via HTML sanitizer bypass
other:Red Hat severity ratingcvssV3_1
  • 2026-06-12T21:02:24.911Z: Reported to Red Hat.
  • 2026-06-12T20:39:47.065Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
apostrophecmssanitize-html< 2.17.4Listed
Weakness

CWE details

CWE-79

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-79 · source CWE mapping

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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