CVE-2026-100671 (GCVE-0-2026-100671)
Vulnerability from cvelistv5 – Published: 2026-09-26 13:23 – Updated: 2026-09-26 13:23
VLAI
EPSS
VEX
Title
Grav before 2.0.25 Session Cookie Theft via Twig Sandbox
Summary
Grav is a flat-file CMS. In versions 2.0.19 through 2.0.24 — and in 2.0.0 through 2.0.18 and 1.7.x only where content Twig has been explicitly enabled — page content authored by a user holding only page-write permission is rendered through a Twig sandbox that allowlists get_cookie(), which returns any cookie sent with the current request, including the visitor's session cookie. Because the read occurs server-side via filter_input(INPUT_COOKIE, ...), the HttpOnly, Secure and SameSite attributes offer no protection. Grav then stores the finished post-Twig output in a page-content cache keyed only on page identity and the configuration checksum, with no session, user or request dimension and no bypass for authenticated visitors. A page published by a page-write user can therefore capture the session identifier of the next administrator who views it, after which the cached output serves that identifier to unauthenticated visitors, who can replay the cookie to authenticate as that administrator. Since 2.0.19, security.twig_content.process_enabled defaults to true and Security::applyTwigContentDefault() derives each page's process.twig flag from that gate, so content Twig runs on every page with no frontmatter or operator action. Fixed in 2.0.25; 1.7.x is outside the backport scope.
Severity
CWE
- CWE-200 - Exposure of Sensitive Information to an Unauthorized Actor
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://github.com/getgrav/grav/security/advisori… | vendor-advisory |
| https://www.vulncheck.com/advisories/grav-before-… | third-party-advisory |
Impacted products
Date Public
2026-09-09 00:00
{
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"product": "grav",
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"versions": [
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"status": "affected",
"version": "0",
"versionType": "semver"
},
{
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"version": "2.0.25",
"versionType": "semver"
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"cpeApplicability": [
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}
],
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"references": [
{
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],
"url": "https://github.com/getgrav/grav/security/advisories/GHSA-pp89-h475-7gj6"
},
{
"name": "VulnCheck Advisory: Grav before 2.0.25 Session Cookie Theft via Twig Sandbox",
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],
"url": "https://www.vulncheck.com/advisories/grav-before-2.0.25-session-cookie-theft-via-twig-sandbox"
}
],
"title": "Grav before 2.0.25 Session Cookie Theft via Twig Sandbox",
"x_generator": {
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}
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"datePublished": "2026-09-26T13:23:35.451Z",
"dateReserved": "2026-09-26T02:34:55.635Z",
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"state": "PUBLISHED"
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}
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"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Grav is a flat-file CMS. In versions 2.0.19 through 2.0.24 \u2014 and in 2.0.0 through 2.0.18 and 1.7.x only where content Twig has been explicitly enabled \u2014 page content authored by a user holding only page-write permission is rendered through a Twig sandbox that allowlists get_cookie(), which returns any cookie sent with the current request, including the visitor\u0027s session cookie. Because the read occurs server-side via filter_input(INPUT_COOKIE, ...), the HttpOnly, Secure and SameSite attributes offer no protection. Grav then stores the finished post-Twig output in a page-content cache keyed only on page identity and the configuration checksum, with no session, user or request dimension and no bypass for authenticated visitors. A page published by a page-write user can therefore capture the session identifier of the next administrator who views it, after which the cached output serves that identifier to unauthenticated visitors, who can replay the cookie to authenticate as that administrator. Since 2.0.19, security.twig_content.process_enabled defaults to true and Security::applyTwigContentDefault() derives each page\u0027s process.twig flag from that gate, so content Twig runs on every page with no frontmatter or operator action. Fixed in 2.0.25; 1.7.x is outside the backport scope."
}
],
"id": "CVE-2026-100671",
"lastModified": "2026-09-26T14:16:50.860",
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"source": "disclosure@vulncheck.com",
"url": "https://github.com/getgrav/grav/security/advisories/GHSA-pp89-h475-7gj6"
},
{
"source": "disclosure@vulncheck.com",
"url": "https://www.vulncheck.com/advisories/grav-before-2.0.25-session-cookie-theft-via-twig-sandbox"
}
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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.
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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