CVE-2026-103321 (GCVE-0-2026-103321)
Vulnerability from cvelistv5 – Published: 2026-09-30 12:19 – Updated: 2026-09-30 12:44
VLAI
EPSS
VEX
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
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-30 12:44 UTC
CWE
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/MISP/MISP/commit/92c7ccc43 | patch |
Impacted products
GCVE extensions
AI-generated
Human-reviewed
Confidence: high
Model
qwen3.8:27b
advisory
bcp-05-x-01bcp-05-x-02
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 |
- Generator
-
patch2vuln.pyon 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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"status": "affected",
"version": "0",
"versionType": "semver"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "reporter",
"value": "Bastien Bossiroy of NCIA"
},
{
"lang": "en",
"type": "remediation developer",
"value": "iglocska"
},
{
"lang": "en",
"type": "remediation developer",
"value": "Claude Opus 4.8"
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eMISP contains a stored cross-site script (XSS) vulnerability in the event graph preview feature.\u003c/p\u003e\u003cp\u003eThe 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.\u003c/p\u003e\u003cp\u003ePreconditions:\u003c/p\u003e\u003cp\u003e- An authenticated MISP user with the ability to create or modify an event graph entry.\u003c/p\u003e\u003cp\u003e- A second user (the victim) who views the event graph and triggers the preview popover.\u003c/p\u003e\u003cp\u003eImpact:\u003c/p\u003e\u003cp\u003e- Execution of arbitrary JavaScript in the victim\u0027s browser within the MISP application context.\u003c/p\u003e\u003cp\u003e- Potential theft of session tokens, cookies, or sensitive data accessible to the victim\u0027s browser.\u003c/p\u003e\u003cp\u003e- Potential for performing actions on behalf of the victim within the MISP application.\u003c/p\u003e\u003cp\u003eAffected: MISP versions prior to the fix (commit applied after v2.5.48).\u003c/p\u003e"
}
],
"value": "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)."
}
],
"impacts": [
{
"capecId": "CAPEC-1",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-1 Cross Site Scripting (XSS)"
}
]
}
],
"metrics": [
{
"cvssV4_0": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "NETWORK",
"baseScore": 8.3,
"baseSeverity": "HIGH",
"privilegesRequired": "LOW",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "HIGH",
"subIntegrityImpact": "HIGH",
"userInteraction": "PASSIVE",
"valueDensity": "NOT_DEFINED",
"vectorString": "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",
"version": "4.0",
"vulnAvailabilityImpact": "NONE",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "HIGH",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-79",
"description": "CWE-79 Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
"lang": "en",
"type": "CWE"
}
]
},
{
"descriptions": [
{
"cweId": "CWE-20",
"description": "CWE-20 Improper Input Validation",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-09-30T12:19:01.829Z",
"orgId": "5a6e4751-2f3f-4070-9419-94fb35b644e8",
"shortName": "CIRCL"
},
"references": [
{
"name": "Security patch",
"tags": [
"patch"
],
"url": "https://github.com/MISP/MISP/commit/92c7ccc43"
}
],
"solutions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eThe 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.\u003c/p\u003e"
}
],
"value": "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."
}
],
"title": "MISP Stored Cross-Site Scripting (XSS) via Unvalidated Event Graph Preview Image",
"x_gcve": [
{
"extensions": {
"bcp-05-x-01": {
"ai_annotations": [
{
"ai_level": "generated",
"description": "Draft vulnerability metadata was generated from a git-format patch using an Ollama-hosted language model. Human validation is required before publication.",
"gna_source": 1,
"models": [
{
"gna_source": 1,
"identifier": "qwen3.8:27b",
"name": "qwen3.8:27b",
"source": "ollama"
}
],
"review_status": "full",
"scope": "record",
"tags": [
"ai-computer-assisted:llm-generated",
"ai-computer-assisted:classification"
]
}
]
},
"bcp-05-x-02": {
"x_patch2vuln": {
"assumptions": [
"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."
],
"capecRationale": [
{
"capecId": "CAPEC-1",
"rationale": "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."
}
],
"commit": "92c7ccc4398a64e61699bd79fb4010703616fc59",
"confidence": "high",
"credits": [
{
"lang": "en",
"type": "reporter",
"value": "Bastien Bossiroy of NCIA"
},
{
"lang": "en",
"type": "remediation developer",
"value": "iglocska"
},
{
"lang": "en",
"type": "remediation developer",
"value": "Claude Opus 4.8"
}
],
"cvssRationale": "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\u0027s browser. SC:H: the attacker can read cookies, tokens, and data in the victim\u0027s session. SI:H: the attacker can perform authenticated actions as the victim. SA:N: no availability impact on the victim\u0027s system.",
"fixSummary": "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.",
"generatedAt": "2026-09-30T11:21:27.655462Z",
"generator": "patch2vuln.py",
"model": "qwen3.8:27b",
"modelComparison": {
"rankings": [
{
"agreementScore": 9,
"assumptionCount": 5,
"confidence": "high",
"model": "qwen3.8:27b",
"score": 6
}
],
"selectedModel": "qwen3.8:27b",
"selectionMethod": "deterministic-consensus-v1",
"selectionNotice": "The selected result is closest to model consensus; this heuristic does not establish factual correctness and human review remains required."
},
"patchSha256": "0ecb893de30056bc3f9609fcb8de43d60b1cedd6a1eea7d6aa53ef6d351d642a",
"patchSummary": "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 \u0027\u003cimg ... src=\"\u0027 + value + \u0027\" /\u003e\u0027) are replaced with jQuery DOM construction using $(\u0027\u003cimg ...\u003e\u0027).prop(\u0027src\u0027, value), which sets the attribute safely without HTML parsing.",
"patchTruncated": false,
"patches": [
{
"commit": "92c7ccc4398a64e61699bd79fb4010703616fc59",
"patchSha256": "0ecb893de30056bc3f9609fcb8de43d60b1cedd6a1eea7d6aa53ef6d351d642a",
"source": "https://github.com/MISP/MISP/commit/92c7ccc43.patch",
"sourceUrl": "https://github.com/MISP/MISP/commit/92c7ccc43.patch",
"subject": "fix: [security] Validate the event graph preview and stop"
}
],
"source": "https://github.com/MISP/MISP/commit/92c7ccc43.patch",
"subject": "fix: [security] Validate the event graph preview and stop",
"tagVersionBoundary": {
"commits_after_fix": 43,
"repository": "https://github.com/MISP/MISP",
"tag": "v2.5.48",
"version": "2.5.48",
"version_type": "semver"
},
"weaknessRationale": [
{
"cweId": "CWE-79",
"rationale": "The stored preview_img value was rendered into an HTML attribute via string concatenation without sufficient neutralization, enabling script injection in the victim\u0027s browser. This is a textbook stored XSS."
},
{
"cweId": "CWE-20",
"rationale": "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."
}
]
}
}
},
"recordType": "advisory",
"vulnId": "GCVE-1-2026-20294"
}
]
}
},
"cveMetadata": {
"assignerOrgId": "5a6e4751-2f3f-4070-9419-94fb35b644e8",
"assignerShortName": "CIRCL",
"cveId": "CVE-2026-103321",
"datePublished": "2026-09-30T12:19:01.829Z",
"dateReserved": "2026-09-30T12:18:54.232Z",
"dateUpdated": "2026-09-30T12:44:22.064Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
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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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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.
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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.
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