ApostropheCMS uploadfs Azure backend leaks account-level SAS token into every public attachment URL (sas: true)

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ApostropheCMS is an open-source Node.js content management system. From 1.25.0 until 1.28.0, uploadfs Azure backend leaks account-level SAS token into every public attachment URL. When uploadfs is configured with the Azure backend and sas: true, createContainer() builds the BlobServiceClient from a URL that embeds the full SAS query string, and Azure SDK v12 derived clients inherit that query string. This issue is fixed in version 1.28.0.

Source published

20 Oct 2026 16:26:21 UTC

Source modified

21 Oct 2026 15:53:38 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · 5.6 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

ApostropheCMS is an open-source Node.js content management system. From 1.25.0 until 1.28.0, uploadfs Azure backend leaks account-level SAS token into every public attachment URL. When uploadfs is configured with the Azure backend and sas: true, createContainer() builds the BlobServiceClient from a URL that embeds the full SAS query string, and Azure SDK v12 derived clients inherit that query string. This issue is fixed in version 1.28.0.

Source published

Oct 20, 2026, 4:26:21 PM (timezone not stated)

Source modified

Oct 21, 2026, 3:53:38 PM (timezone not stated)

Observed here

7 Nov 2026 04:34:09 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 5.6 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

ApostropheCMS is an open-source Node.js content management system. From 1.25.0 until 1.28.0, uploadfs Azure backend leaks account-level SAS token into every public attachment URL. When uploadfs is configured with the Azure backend and sas: true, createContainer() builds the BlobServiceClient from a URL that embeds the full SAS query string, and Azure SDK v12 derived clients inherit that query string. This issue is fixed in version 1.28.0.

Source published

20 Oct 2026 17:17:36 UTC

Source modified

21 Oct 2026 16:17:23 UTC

Observed here

25 Oct 2026 05:17:18 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 5.6 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

## Summary When uploadfs is configured with the Azure backend and `sas: true` (a supported configuration introduced in uploadfs 1.25.0), `createContainer()` builds the `BlobServiceClient` from a URL that embeds the full SAS query string, and Azure SDK v12 derived clients inherit that query string. As a result, `getUrl()` returns a base URL carrying the complete account/container SAS signature (`?sv=...&sig=...`), and Apostrophe's `attachment.url()` prepends it to every public attachment link — broadcasting a container-level SAS credential (commonly `sp=rwdlac`, full read/write/delete/list) to every site visitor, including anonymous ones. Anyone who can see an attachment URL can read, overwrite, delete, and list every blob in the container for the SAS lifetime. A companion functional bug (blob path appended after the query string, producing broken URLs) shows this code path was never exercised end to end. Shared-key mode (default) and non-Azure backends are not affected. Verified at commit `5a3746aaed49761e171c2cbfe793267c959829fd` (uploadfs 1.27.0 in the apostrophe monorepo). ## Details Root cause: a credential-bearing client URL is reused as the public base URL. The chain: - Credential-embedded client: [azure.js#L123-L125](https://github.com/apostrophecms/apostrophe/blob/5a3746aaed49761e171c2cbfe793267c959829fd/packages/uploadfs/lib/storage/azure.js#L123-L125) — `new BlobServiceClient("https://<account>.blob.core.windows.net?<SAS query string>")` where `cluster.key` is the full SAS string including `sig` - Leak point: [azure.js#L513-L520](https://github.com/apostrophecms/apostrophe/blob/5a3746aaed49761e171c2cbfe793267c959829fd/packages/uploadfs/lib/storage/azure.js#L513-L520) — `getUrl()` takes `getContainerClient(...).getBlobClient('').url` as `baseUrl`; SDK v12 derived clients inherit the SAS query string, so `baseUrl` already contains `?sv=...&sig=...` - Public exposure: [attachment/index.js#L694](https://github.com/apostrophecms/apostrophe/blob/5a3746aaed49761e171c2cbfe793267c959829fd/packages/apostrophe/modules/@apostrophecms/attachment/index.js#L694) — `attachment.url()` = `uploadfs.getUrl() + path` for every rendered attachment link; [attachment/index.js#L1503](https://github.com/apostrophecms/apostrophe/blob/5a3746aaed49761e171c2cbfe793267c959829fd/packages/apostrophe/modules/@apostrophecms/attachment/index.js#L1503) — `getBrowserData()` also ships `uploadsUrl` to every logged-in editor session - Companion bug: the blob path is appended **after** the query string (`/container/?sv=...&sig=XXX/attachments/id-name`), so these URLs are also broken — evidence the 1.25.0 code path was never tested Attack surface: every public page rendering attachment URLs (images, download links), plus the `uploadsUrl` delivered to editor sessions. The leak is passive and unconditional — no action required from the victim beyond serving a page. The credential further propagates through HTML source, logs, Referer headers, and CDN/proxy access logs. **Suggested remediation:** 1. Strip the query string before building public URLs: `const u = new URL(blob.svc.getContainerClient(...).getBlobClient('').url); u.search = '';` (or compose `accountUrl + '/' + container` manually), and append the blob path to the pathname, not after the query. 2. Document that SAS mode must use least privilege (read-only, ideally `sr=b` per-blob), and prefer generating short-lived per-blob read-only signed URLs via `generateBlobSASQueryParameters` instead of embedding a service-level SAS in permanent public URLs. ## PoC Full PoC posted as the first comment below (`poc.js` + README; offline, no Azure account needed). It replicates the library's exact two steps with the declared dependency `@azure/storage-blob@12`: 1. `npm install @azure/storage-blob@12 && node poc.js` 2. The script constructs `new BlobServiceClient("https://myaccount.blob.core.windows.net?sv=...&sig=FAKESIGNATURE")` exactly like `createContainer()`, then evaluates the `getUrl()` logic (`getContainerClient('uploads-container').getBlobClient('').url`) and asserts the resulting base URL still contains the `sig` parameter. 3. Observed output (exit code 0): ``` baseUrl: https://myaccount.blob.core.windows.net/uploads-container/?sv=2021-06-08&ss=b&srt=co&sp=rwdlac&se=2099-01-01&sig=FAKESIGNATURE attachment URL as served to visitors: https://myaccount.blob.core.windows.net/uploads-container/?sv=2021-06-08&ss=b&srt=co&sp=rwdlac&se=2099-01-01&sig=FAKESIGNATURE/attachments/abc123-photo.jpg ``` The produced URL both leaks the token (`sv`…`sig`) and demonstrates the broken path placement. Cross-checking `attachment/index.js` confirms this URL reaches public pages unmodified. ## Impact - **What it is:** insufficiently protected credentials (CWE-522) leading to information exposure (CWE-200). A container-level SAS token — commonly granted `sp=rwdlac` (read/write/delete/list/ACL) — is disclosed to every site visitor including anonymous users, valid for the SAS lifetime (often years). Holders can read, overwrite, delete, and enumerate every attachment in the container; the library applies no narrowing. - **Who is impacted:** Apostrophe sites using uploadfs with the Azure backend and `sas: true` (introduced in 1.25.0; present through 1.27.0). Default shared-key mode and other backends are unaffected. When the SAS is provisioned read-only, the impact reduces to unauthenticated read/download of all attachments. --- Reported by **Kimi Security Team** ([email protected]).

Source published

20 Oct 2026 18:20:35 UTC

Source modified

20 Oct 2026 18:30:03 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

Publisher rating · MODERATE