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CVE-2026-53607 apostrophecms CVE debrief

ApostropheCMS, an open-source Node.js content management system, has a vulnerability in versions up to and including 4.30.0. When the `prettyUrls: true` option is enabled on `@apostrophecms/file`, a feature for serving uploaded files at clean URLs, an unauthenticated remote attacker can exploit this to pivot the Apostrophe process to issue outbound HTTP requests against any host reachable on the private network. The vulnerability is rated as LOW with a CVSS score of 3.7.

Vendor
apostrophecms
Product
apostrophe
CVSS
LOW 3.7
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-12
Original CVE updated
2026-06-15
Advisory published
2026-06-12
Advisory updated
2026-06-15

Who should care

Users of ApostropheCMS, especially those who have enabled the `prettyUrls: true` option on `@apostrophecms/file`, should be aware of this vulnerability and take necessary actions to mitigate it.

Technical summary

The public pretty-URL handler in ApostropheCMS builds the upstream URL using the raw `Host` HTTP request header, which is fully attacker-controlled. This allows an attacker to issue outbound HTTP requests against any host reachable on the private network. The path component of the URL is constrained to `/uploads/attachments/<cuid>-<slug>.<ext>`, which limits the impact but still allows for blind SSRF attacks.

Defensive priority

LOW

Recommended defensive actions

  • Update to a patched version of ApostropheCMS as soon as available.
  • Disable the `prettyUrls: true` option on `@apostrophecms/file` if not necessary.
  • Monitor for suspicious outbound HTTP requests from the Apostrophe process.

Evidence notes

The CVE record and NVD detail can be found at [cve-org] and [nvd], respectively. Additional information is available at [ref-4].

Sources and references

Verified primary and authoritative sources

  • CVE-2026-53607 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-53607

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-53607 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-53607

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.