Vulnerability-Lookup

GHSA-W4MV-4X7W-VPVV

Vulnerability from github – Published: 2026-09-30 15:31 – Updated: 2026-09-30 15:31

Details

MISP contains a stored cross-site script (XSS) vulnerability in the event graph preview feature.

The event graph preview image field was accepted and stored without server-side validation. On the client side, the stored value was rendered into an HTML img element's src attribute via string concatenation, allowing a crafted value to break out of the attribute context and inject arbitrary script.

Preconditions:

An authenticated MISP user with the ability to create or modify an event graph entry.
A second user (the victim) who views the event graph and triggers the preview popover.

Impact:

Execution of arbitrary JavaScript in the victim's browser within the MISP application context.
Potential theft of session tokens, cookies, or sensitive data accessible to the victim's browser.
Potential for performing actions on behalf of the victim within the MISP application.

Affected: MISP versions prior to the fix (commit applied after v2.5.48).

Severity

8.3 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:H/VA:N/SC:H/SI:H/SA:N

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{
  "affected": [],
  "aliases": [
    "CVE-2026-103321"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-30T13:17:18Z",
    "severity": "HIGH"
  },
  "details": "MISP contains a stored cross-site script (XSS) vulnerability in the event graph preview feature.\n\nThe event graph preview image field was accepted and stored without server-side validation. On the client side, the stored value was rendered into an HTML img element\u0027s src attribute via string concatenation, allowing a crafted value to break out of the attribute context and inject arbitrary script.\n\nPreconditions:\n\n- An authenticated MISP user with the ability to create or modify an event graph entry.\n\n- A second user (the victim) who views the event graph and triggers the preview popover.\n\nImpact:\n\n- Execution of arbitrary JavaScript in the victim\u0027s browser within the MISP application context.\n\n- Potential theft of session tokens, cookies, or sensitive data accessible to the victim\u0027s browser.\n\n- Potential for performing actions on behalf of the victim within the MISP application.\n\nAffected: MISP versions prior to the fix (commit applied after v2.5.48).",
  "id": "GHSA-w4mv-4x7w-vpvv",
  "modified": "2026-09-30T15:31:24Z",
  "published": "2026-09-30T15:31:24Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-103321"
    },
    {
      "type": "WEB",
      "url": "https://github.com/MISP/MISP/commit/92c7ccc43"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:H/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-103321 (GCVE-0-2026-103321)

Vulnerability from cvelistv5 – Published: 2026-09-30 12:19 – Updated: 2026-09-30 12:44

Title

MISP Stored Cross-Site Scripting (XSS) via Unvalidated Event Graph Preview Image

Summary

MISP contains a stored cross-site script (XSS) vulnerability in the event graph preview feature. The event graph preview image field was accepted and stored without server-side validation. On the client side, the stored value was rendered into an HTML img element's src attribute via string concatenation, allowing a crafted value to break out of the attribute context and inject arbitrary script. Preconditions: - An authenticated MISP user with the ability to create or modify an event graph entry. - A second user (the victim) who views the event graph and triggers the preview popover. Impact: - Execution of arbitrary JavaScript in the victim's browser within the MISP application context. - Potential theft of session tokens, cookies, or sensitive data accessible to the victim's browser. - Potential for performing actions on behalf of the victim within the MISP application. Affected: MISP versions prior to the fix (commit applied after v2.5.48).

Severity

8.3 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:H/VA:N/SC:H/SI:H/SA:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-30 12:44 UTC

CWE

CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-20 - Improper Input Validation

Assigner

CIRCL ENISA root Scorecard

References

1 reference

URL	Tags
https://github.com/MISP/MISP/commit/92c7ccc43	patch

Impacted products

1 product

Vendor	Product	Version
MISP	MISP	Affected: 0 , < 2.5.48 (semver) cpe:2.3:a:misp:misp::::::::

Credits

Bastien Bossiroy of NCIA iglocska Claude Opus 4.8

GCVE extensions

AI-generated Human-reviewed Confidence: high Model qwen3.8:27b advisory bcp-05-x-01bcp-05-x-02

AI involvement GCVE-BCP-05-X-01

Whole record AI-generated Human-reviewed GNA-1

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

Generator: patch2vuln.py on 2026-09-30 11:21
Model: qwen3.8:27b
Input: https://github.com/MISP/MISP/commit/92c7ccc43.patch 0ecb893de300…
Confidence: high

Commit	Subject	Patch SHA-256
`92c7ccc4398a`	fix: [security] Validate the event graph preview and stop	`0ecb893de300…`

Fix summary

The vulnerability is remediated by enforcing strict server-side validation of the preview image field, restricting it to a well-formed base64-encoded PNG data URL, and by replacing the client-side string-concatenation rendering with DOM-based attribute assignment that does not interpret the value as HTML.

Patch summary

In app/Model/EventGraph.php, a new validation rule is added for the preview_img field requiring it to match the regex /^data:image\/png;base64,[A-Za-z0-9+\/]*={0,2}$/ (allowing empty). In app/webroot/js/event-graph.js, two occurrences of string-concatenated img tag construction (return '<img ... src="' + value + '" />') are replaced with jQuery DOM construction using $('<img ...>').prop('src', value), which sets the attribute safely without HTML parsing.

CVSS rationale

AV:N: exploited over the network via the MISP web interface. AC:L: no race conditions or special conditions required; storing a crafted value and viewing the graph is straightforward. AT:N: no manipulation of the attack target needed. PR:L: attacker needs a low-privilege authenticated MISP account to create/modify an event graph. UI:P: the victim passively triggers the XSS by viewing the event graph preview (hovering a button), a normal workflow action. VC/VI/VA:N: the MISP server itself is not compromised; the impact is in the victim's browser. SC:H: the attacker can read cookies, tokens, and data in the victim's session. SI:H: the attacker can perform authenticated actions as the victim. SA:N: no availability impact on the victim's system.

Weakness rationale

CWE-79 The stored preview_img value was rendered into an HTML attribute via string concatenation without sufficient neutralization, enabling script injection in the victim's browser. This is a textbook stored XSS.
CWE-20 The server accepted and persisted the preview_img field without any format validation, allowing arbitrary content to be stored and later rendered. The fix adds a strict regex validation rule.

Attack pattern rationale

CAPEC-1 The patch directly addresses a stored XSS where attacker-controlled data is rendered into a web page without proper encoding or validation. CAPEC-1 is the canonical attack pattern for XSS and is the closest match. No uncertainty in this mapping; the commit message explicitly identifies the issue as stored XSS.

Assumptions to verify

The affected version range is inferred from the tag_version_boundary (v2.5.48 with 43 commits after the fix); the exact fixed release version is not stated in the patch metadata.
PR:L assumes the attacker needs at least a basic authenticated MISP account to create or modify an event graph entry; the patch does not specify the exact permission level required.
UI:P assumes the victim triggers the XSS by viewing the event graph preview as part of normal workflow (hovering the plot button), which is a passive interaction rather than an active click on a crafted link.
The CAPEC-1 mapping is direct and unambiguous given the explicit stored XSS identification in the commit message.
The Co-Authored-By line referencing Claude Opus 4.8 is treated as a tool credit per the commit metadata; it is not a human contributor.

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	high	5

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JSON

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                "subject": "fix: [security] Validate the event graph preview and stop",
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    "state": "PUBLISHED"
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}

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.

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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

GHSA-W4MV-4X7W-VPVV

CVE-2026-103321 (GCVE-0-2026-103321)

Fix summary

Patch summary

CVSS rationale

Weakness rationale

Attack pattern rationale

Assumptions to verify

Model comparison

Tags

Sightings

Nomenclature

Related by attack behaviour