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Response snapshot Oct 26, 2026, 22:06 UTC

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VulnerabilityCVE-2026-113652

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

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.

At a glance

Exploited
Not known
Severity
5.6 Medium (CVSS 3.1)
Chance of exploitation
0.3% in the next 30 days
Sources
1 source

What to do

GitHub lists first patched versions: uploadfs: 1.28.0. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-hhph-8536-gfq5 (opens a new tab)

What happened

## 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.

Continue reading

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:// .blob.core.windows.net? ")` 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** (bug-report@moonshot.ai).

Affected package ranges reported by GitHub: uploadfs: >= 1.25.0, < 1.28.0

Scores and how they were measured

CVSS base severity

5.6

Version 3.1As of

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

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.3%

Scored Percentile 20.0%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-hhph-8536-gfq5 (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-hhph-8536-gfq5, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  3. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-hhph-8536-gfq5, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  4. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-hhph-8536-gfq5, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  5. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-hhph-8536-gfq5, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  6. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-hhph-8536-gfq5, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  7. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-hhph-8536-gfq5, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  8. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-hhph-8536-gfq5, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  9. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-hhph-8536-gfq5, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  10. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-113652, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 20). ApostropheCMS uploadfs Azure backend leaks account-level SAS token into every public attachment URL (sas: true) (CVE-2026-113652). https://kevwire.com/record/CVE-2026-113652

MLA

"ApostropheCMS uploadfs Azure backend leaks account-level SAS token into every public attachment URL (sas: true) (CVE-2026-113652)." KEVWire, 20 Oct. 2026, kevwire.com/record/CVE-2026-113652.

Chicago

KEVWire. "ApostropheCMS uploadfs Azure backend leaks account-level SAS token into every public attachment URL (sas: true) (CVE-2026-113652)." Last modified October 20, 2026. https://kevwire.com/record/CVE-2026-113652.

Evidence summary (plain text)

ApostropheCMS uploadfs Azure backend leaks account-level SAS token into every public attachment URL (sas: true) (Oct 20, 2026).
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).
CVSS 5.6 (version 3.1; evidence as of Oct 20, 2026; https://github.com/advisories/GHSA-hhph-8536-gfq5).
EPSS 0.3% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-113652&date=2026-10-26).
Sources:
GitHub-reviewed advisory GHSA-hhph-8536-gfq5: https://github.com/advisories/GHSA-hhph-8536-gfq5
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMlQwODoyNzoyM1rOAAYp9A%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMTozNTo1OFrOAAfwCQ%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMTozMDoxM1rOAAfv2A%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMToyODowOVrOAAfv1g%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMToyNDoyMFrOAAfv1Q%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDo0NTowN1rOAAfvzQ%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDozMDoyNlrOAAfvxw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDowMzo1N1rOAAfvxQ%3D%3D
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-113652&date=2026-10-26
Record ID: CVE-2026-113652.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 26, 2026, 19:40 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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