elFinder: SSRF protection bypass via DNS rebinding in the fsock_get_contents() fallback

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-81889: 0.55% estimated exploitation activity in the next 30 days; percentile 46.07 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

poc.zip Summary elFinder 2.1.69 is vulnerable to a Server-Side Request Forgery (SSRF) protection bypass when PHP cURL is unavailable and URL uploads use the fsockgetcontents() fallback. An attacker who can submit a URL for server-side upload can use an attacker-controlled DNS hostname that initially resolves to an allowed public IP address and subsequently resolves to a loopback or private IP address. The URL validation checks the first resolved IP, but fsockgetcontents() opens the actual connection using the original hostname. This causes a second DNS resolution and allows the connection to reach an address different from the one that was validated. The response from the internal service is saved as an uploaded file and can be read through elFinder. This makes the demonstrated issue a non-blind SSRF. The most accurate classification is: Vulnerability: SSRF protection bypass Exploitation technique: DNS rebinding Root cause: TOCTOU/double DNS resolution without IP pinning Affected…

Published by the source

31 Aug 2026, 20:28 UTC

Last modified by the source

31 Aug 2026, 20:55 UTC

Source last checked

26 Oct 2026, 14:50 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-8x3q-jpjh-qh5c

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-8x3q-jpjh-qh5c

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# Patch Next advisory brief: CVE-2026-81889

Advisory: elFinder: SSRF protection bypass via DNS rebinding in the `fsock_get_contents()` fallback
IDs: CVE-2026-81889, GHSA-8x3q-jpjh-qh5c
Record: https://patchnext.com/advisories/cve-2026-81889 (revision 2, source checked 26 Oct 2026, 14:50 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.6)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: studio-42/elfinder 2.1.70. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist studio-42/elfinder: affected <= 2.1.69; fixed in 2.1.70

## Suggested inspection (read-only)
- Packagist studio-42/elfinder: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on studio-42/elfinder.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-8x3q-jpjh-qh5c (OSV record GHSA-8x3q-jpjh-qh5c lists affected ranges: Packagist studio-42/elfinder >=0 <2.1.70 (fixed))
- Verified: https://github.com/advisories/GHSA-8x3q-jpjh-qh5c (GitHub-reviewed advisory GHSA-8x3q-jpjh-qh5c lists affected ranges: Packagist studio-42/elfinder >=0 <=2.1.69)

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