FrankenPHP: Cross-request PHP session ID leak in worker mode when the session extension is a shared module

Exploitation

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

CVSS

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

EPSS

• CVE-2026-82416: 0.29% estimated exploitation activity in the next 30 days; percentile 21.91 (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.

Summary In worker mode under concurrency, FrankenPHP can hand a PHP session id from one request to another when PHP's session extension is loaded as a shared module instead of being statically linked into the FrankenPHP binary. A request presenting Cookie: session=A can have sessionid() resolve to B (a different concurrent client's id) or to a stale id from a previous request served by the same worker thread. Impact - Security: cross-user session exposure / session hijacking in worker mode. Same impact class as CVE-2026-24894. - Functional: users are intermittently logged out; their cookie's session is ignored and they receive a foreign or empty session. Affected / not affected Exposure is determined by how the session extension is linked in the PHP build FrankenPHP is compiled against, not by the FrankenPHP release: - Affected: any build where the session extension is not visible to FrankenPHP at compile time, i.e. loaded as a shared / out-of-tree module (extension=session in an…

Published by the source

15 Oct 2026, 20:14 UTC

Last modified by the source

19 Oct 2026, 21:31 UTC

Source last checked

26 Oct 2026, 15:32 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-v3ph-cgqh-r8p5

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GO-2026-6797

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-v3ph-cgqh-r8p5

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# Patch Next advisory brief: CVE-2026-82416

Advisory: FrankenPHP: Cross-request PHP session ID leak in worker mode when the session extension is a shared module
IDs: CVE-2026-82416, GHSA-v3ph-cgqh-r8p5
Record: https://patchnext.com/advisories/cve-2026-82416 (revision 3, source checked 26 Oct 2026, 15:32 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/dunglas/frankenphp 1.12.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/dunglas/frankenphp: affected <= 1.12.4; fixed in 1.12.5

## Suggested inspection (read-only)
- Go github.com/dunglas/frankenphp: 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 github.com/dunglas/frankenphp.
- 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/GO-2026-6797 (OSV record GO-2026-6797 lists affected ranges: Go github.com/dunglas/frankenphp >=0 <1.12.5 (fixed))
- Verified: https://osv.dev/vulnerability/GHSA-v3ph-cgqh-r8p5 (OSV record GHSA-v3ph-cgqh-r8p5 lists affected ranges: Go github.com/dunglas/frankenphp >=0 <1.12.5 (fixed))
- Verified: https://github.com/advisories/GHSA-v3ph-cgqh-r8p5 (GitHub-reviewed advisory GHSA-v3ph-cgqh-r8p5 lists affected ranges: Go github.com/dunglas/frankenphp >=0 <=1.12.4)

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