GCVE-1-2026-20178 (CVE-2026-88921)
Vulnerability from gna-1 – Published: 2026-09-10 13:41 – Updated: 2026-09-10 14:24
VLAI
EPSS
VEX
Title
MISP: Unescaped HTML Injection in PDF Report Element Rendering
Summary
MISP contains an HTML injection vulnerability in the MISPElementHTMLFormatterTool component, which is responsible for rendering MISP element references (attributes, objects, and tags) into inline HTML during PDF report export via the convert_markdown_to_pdf module. The attribute(), objectAttribute(), object(), and tag() methods interpolated user-controlled fields (attribute type, attribute value, object name, object relation, tag name, tag colour, and tag text colour) directly into HTML templates without applying HTML entity encoding. An authenticated user with the ability to create or modify MISP attributes, objects, or tags could embed arbitrary HTML markup in these fields. When a report containing such elements was exported to PDF, the unescaped content was rendered as live HTML rather than inert text, potentially injecting script tags, breaking the document structure, or altering the visual content of the exported report. Additionally, the attribute() method contained a template with hardcoded sample values ("domain-ip" and "google.com") instead of format placeholders, meaning every plain attribute reference in a PDF displayed the sample text rather than the actual indicator value, constituting a data-integrity defect in the exported document. The vulnerability requires an authenticated actor with write access to MISP elements and a subsequent PDF export of a report referencing those elements. The security impact is primarily to the integrity of the exported document and, depending on the HTML-to-PDF rendering engine, potential execution of injected markup during the conversion step.
Version affected: ≤2.5.45
Severity
CWE
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/MISP/MISP/commit/949744a4b | patch |
Impacted products
GCVE extensions
AI-generated
Draft
Confidence: medium
Model
qwen3.8:27b
advisory
bcp-05-x-01bcp-05-x-02
AI involvement
GCVE-BCP-05-X-01
Draft vulnerability metadata was generated from a git-format patch using an Ollama-hosted language model. Human validation is required before publication.
ai-computer-assisted:llm-generatedai-computer-assisted:classification
| Model | Source | Identifier |
|---|---|---|
| qwen3.8:27b | ollama | qwen3.8:27b |
Patch provenance
GCVE-BCP-05-X-02
This metadata was derived automatically from a patch and is still a draft: human review is required before it can be considered authoritative.
- Generator
-
patch2vuln.pyon 2026-09-10 13:06 - Model
qwen3.8:27b- Input
-
https://github.com/MISP/MISP/commit/949744a4b.patch
300efd40407c… - Confidence
- medium
| Commit | Subject | Patch SHA-256 |
|---|---|---|
949744a4b6de
|
fix: [event-report] Render and escape MISP element references | 300efd40407c… |
Fix summary
The fix applies HTML entity encoding (via the h() helper, which wraps htmlspecialchars with ENT_QUOTES and UTF-8) to every user-controlled value interpolated into the HTML templates in the MISPElementHTMLFormatterTool. This ensures that attribute types, values, object names, relations, tag names, and colour values are treated as inert data and cannot inject markup or break out of the surrounding span/style context. The hardcoded sample values in the attribute() template are replaced with proper %s format placeholders so that the actual element data is rendered. Comprehensive unit tests are added to verify both correct rendering and escaping of hostile inputs across all four formatter methods.
Patch summary
In MISPElementHTMLFormatterTool.php: (1) the attribute() template's hardcoded 'domain-ip' and 'google.com' strings are replaced with %s placeholders; (2) all sprintf arguments in attribute(), objectAttribute(), object(), and tag() are wrapped with h() to HTML-encode the interpolated values (attribute type, value, object name, object_relation, tag name, colour, text_colour). A new test file MISPElementHTMLFormatterToolTest.php is added with 123 lines of PHPUnit tests covering: correct rendering of real values, HTML escaping of hostile payloads (script tags, span-breaking sequences, CSS attribute breakout via quotes), foreign-tag detection, and placeholder behaviour for objects without attributes.
CVSS rationale
AV:N: MISP is a network-accessible web application. AC:L: The attacker only needs to create or modify a MISP element with a crafted value; no race conditions or special timing are required. AT:N: No manipulation of the attack target is needed. PR:L: The attacker requires an authenticated account with permission to create or modify MISP attributes, objects, or tags. UI:N: The victim performs a normal, expected action (exporting a report to PDF); no unusual interaction is required to trigger the rendering of the injected content. VC:N: The primary impact is on the output document, not on reading confidential system data. VI:L: The integrity of the exported PDF is compromised by injected markup or incorrect data (hardcoded sample values). VA:N: No denial-of-service impact is evident. SC:N: No confirmed cross-system confidentiality impact. SI:L: The integrity of the exported document (a secondary asset) is affected; injected content could mislead readers or, if the PDF renderer executes scripts, affect the rendering environment. SA:N: No security-relevant impact on other systems is established by the evidence.
Weakness rationale
- CWE-79 User-controlled MISP element values (attribute values, object names, tag names, tag colours) are interpolated into HTML output without encoding, allowing injection of arbitrary HTML markup into the rendered document. Although the output target is a PDF rather than a browser page, the mechanism is identical to stored XSS: untrusted data is embedded in an HTML context without neutralization.
- CWE-116 The root cause is the absence of output encoding (htmlspecialchars) on all interpolated values in the HTML template strings. The tag() method additionally failed to escape colour values that are placed inside a CSS style attribute, enabling attribute-breakout injection.
Assumptions to verify
- The HTML-to-PDF rendering pipeline (convert_markdown_to_pdf) is assumed to render the generated HTML in a context where injected markup could be interpreted (e.g., headless browser or HTML-aware converter); if a purely static renderer is used, the impact is limited to document corruption.
- The attacker is assumed to have an authenticated MISP account with write access to attributes, objects, or tags; the specific role or permission level required is not stated in the patch.
- The exact fixed version is not specified in the patch metadata; the tag boundary (v2.5.46, 187 commits before the fix) indicates the fix post-dates v2.5.46 but the precise release is unknown.
- UI:N is assigned on the assumption that triggering the PDF export is a normal, expected user action and does not constitute a special interaction requirement beyond routine use of the application.
Model comparison
Selected qwen3.8:27b
by deterministic-consensus-v1
The selected result is closest to model consensus; this heuristic does not establish factual correctness and human review remains required.
| Model | Score | Agreement | Confidence | Assumptions |
|---|---|---|---|---|
qwen3.8:27b |
6 | 9 | medium | 4 |
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},
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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