GHSA-767H-63J4-5226
Vulnerability from github – Published: 2026-07-13 17:00 – Updated: 2026-07-13 17:00Description
The normal download_your_data flow requires the requester to be logged in as the export owner, but the resulting Active Storage blob redirect URL can be replayed without authentication by anyone who obtains it.
Technical description
This private export flow turns an authenticated, user-scoped download into a reusable bearer link because the protected Decidim endpoint redirects to the underlying Active Storage blob URL. Decidim::DownloadYourDataController#download_file correctly scopes the export record to current_user, so the wrapper route itself is not directly accessible to another user. However, once the owner
performs that authenticated GET request, the response redirects to a signed Active Storage URL that is no longer bound to the user session. Anyone who learns that URL can replay it and retrieve the file without being logged in as the export owner.
Because the blob redirect URL is delivered through a GET request and appears in the redirect chain, it is more likely to leak through browser history, logs, proxy tooling, screenshots, copied links, support transcripts, or other client-side handling of URLs.
Reproduction steps:
Step 1. Generate or locate a completed export in the Web UI.
1. Sign in as user@example.org at http://localhost:3001/users/sign_in.
2. Open http://localhost:3001/download_your_data.
3. Request a new export from the page and wait until the export becomes downloadable.
4. Open the completed export entry from the list and copy its wrapper URL, for example http://localhost:3001/download_your_data/download?uuid=07286e61-932d-46d4-bd74-bcd1340c503f.
Step 2. Download through the authenticated wrapper route. 1. While still signed in as user@example.org, open the wrapper URL in the browser. 2. Confirm that this Decidim route requires the owner session and is not directly usable when logged out or when logged in as another user.
Step 3. Capture the final bearer URL in the redirect chain.
- In DevTools Network or Burp, inspect the redirect sequence for the wrapper request.
- Copy the Active Storage redirect URL, typically matching
http://localhost:3001/rails/active_storage/blobs/redirect/<SIGNED_ID>/<FILENAME>. - Note that the Active Storage redirect URL is no longer protected by the Decidim ownership check.
Step 4. Replay the final file URL without authentication.
1. Open a private window or separate browser with no Decidim session.
2. Paste the copied http://localhost:3001/rails/active_storage/blobs/redirect/<SIGNED_ID>/<FILENAME> URL.
3. Confirm the export file still downloads even though you are not logged in as the export owner.
Impact
Personal data exports can be retrieved through leakage channels such as browser history, logs, referrers, screenshots, copied links, support transcripts, intercepted email content, or other client-side disclosure of the GET URL.
Patches
See https://github.com/decidim/decidim/pull/16680
Workarounds
Disable Private Downloads URLs
Reference
OWASP A01:2021 Broken Access Control
Credits
This issue was discovered in a security audit organized by the Decidim Association and made by Radically Open Security against Decidim financed by NGI.
{
"affected": [
{
"package": {
"ecosystem": "RubyGems",
"name": "decidim-core"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.30.9"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "RubyGems",
"name": "decidim-core"
},
"ranges": [
{
"events": [
{
"introduced": "0.31.0.rc1"
},
{
"fixed": "0.31.5"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "RubyGems",
"name": "decidim-core"
},
"ranges": [
{
"events": [
{
"introduced": "0.32.0.rc1"
},
{
"fixed": "0.32.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-45377"
],
"database_specific": {
"cwe_ids": [
"CWE-200"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-13T17:00:08Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "## Description\n\nThe normal `download_your_data` flow requires the requester to be logged in as the export owner, but the resulting Active Storage blob redirect URL can be replayed without authentication by anyone who obtains it.\n\n## Technical description\n \nThis private export flow turns an authenticated, user-scoped download into a reusable bearer link because the protected Decidim endpoint redirects to the underlying Active Storage blob URL. `Decidim::DownloadYourDataController#download_file` correctly scopes the export record to `current_user`, so the wrapper route itself is not directly accessible to another user. However, once the owner\nperforms that authenticated GET request, the response redirects to a signed Active Storage URL that is no longer bound to the user session. Anyone who learns that URL can replay it and retrieve the file without being logged in as the export owner.\n\nBecause the blob redirect URL is delivered through a GET request and appears in the redirect chain, it is more likely to leak through browser history, logs, proxy tooling, screenshots, copied links, support transcripts, or other client-side handling of URLs.\n\nReproduction steps:\n\nStep 1. Generate or locate a completed export in the Web UI.\n1. Sign in as `user@example.org` at `http://localhost:3001/users/sign_in`.\n2. Open `http://localhost:3001/download_your_data`.\n3. Request a new export from the page and wait until the export becomes downloadable.\n4. Open the completed export entry from the list and copy its wrapper URL, for example `http://localhost:3001/download_your_data/download?uuid=07286e61-932d-46d4-bd74-bcd1340c503f `.\n\nStep 2. Download through the authenticated wrapper route.\n1. While still signed in as user@example.org, open the wrapper URL in the browser.\n2. Confirm that this Decidim route requires the owner session and is not directly usable when logged out or when logged in as another user.\n\nStep 3. Capture the final bearer URL in the redirect chain.\n\n1. In DevTools Network or Burp, inspect the redirect sequence for the wrapper request.\n2. Copy the Active Storage redirect URL, typically matching `http://localhost:3001/rails/active_storage/blobs/redirect/\u003cSIGNED_ID\u003e/\u003cFILENAME\u003e`.\n3. Note that the Active Storage redirect URL is no longer protected by the Decidim ownership check.\n\nStep 4. Replay the final file URL without authentication.\n1. Open a private window or separate browser with no Decidim session.\n2. Paste the copied `http://localhost:3001/rails/active_storage/blobs/redirect/\u003cSIGNED_ID\u003e/\u003cFILENAME\u003e` URL.\n3. Confirm the export file still downloads even though you are not logged in as the export owner.\n\n### Impact\n\nPersonal data exports can be retrieved through leakage channels such as browser history, logs, referrers, screenshots, copied links, support transcripts, intercepted email content, or other client-side disclosure of the GET URL.\n\n### Patches\n\nSee https://github.com/decidim/decidim/pull/16680 \n\n### Workarounds\n\nDisable Private Downloads URLs\n\n### Reference\n\nOWASP A01:2021 Broken Access Control\n\n### Credits\n\nThis issue was discovered in a security audit organized by the [Decidim Association](https://decidim.org) and made by [Radically Open Security](https://www.radicallyopensecurity.com/) against Decidim financed by [NGI](https://ngi.eu/).",
"id": "GHSA-767h-63j4-5226",
"modified": "2026-07-13T17:00:08Z",
"published": "2026-07-13T17:00:08Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/decidim/decidim/security/advisories/GHSA-767h-63j4-5226"
},
{
"type": "WEB",
"url": "https://github.com/decidim/decidim/pull/16680"
},
{
"type": "PACKAGE",
"url": "https://github.com/decidim/decidim"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Decidim: Private exports can be downloaded through reusable links"
}
Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
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.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
How durations are calculated
Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.
Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.
Loading timeline…
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.