goshs: Share-link ?token=… redemption races past download limit

Exploitation

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

CVSS

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

EPSS

• CVE-2026-50139: 0.26% estimated exploitation activity in the next 30 days; percentile 17.37 (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.

Share-link ?token=… redemption races past download limit Ecosystem: Go Package: goshs.de/goshs/v2 (github.com/patrickhener/goshs) Affected: <= v2.0.9 (every release that shipped the share-link feature) Summary ShareHandler reads the share token's DownloadLimit under RLock, releases the lock, serves the file, then re-acquires the lock to increment the counter. Concurrent requests all read the same Downloaded/DownloadLimit snapshot, all pass the check, and all are served — exceeding the operator's intended cap. Details httpserver/handler.go:968-1018: Between line 978 (RUnlock) and line 1008 (Lock), any number of goroutines can interleave and each observes the same pre-increment limit. Proof of concept Reproduced 5/5 times in a row on a 2026-era M-series Mac during verification. Impact A "single-use" share intended to deliver a one-shot secret can be redeemed N times by N concurrent clients. Combined with any token-leak vector (mail forwarding, browser history, intercepted link, etc.)…

Published by the source

1 Jul 2026, 21:59 UTC

Last modified by the source

1 Jul 2026, 21:59 UTC

Source last checked

26 Oct 2026, 15:24 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-j48m-h7xq-2xpj

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# Patch Next advisory brief: CVE-2026-50139

Advisory: goshs: Share-link ?token=… redemption races past download limit
IDs: CVE-2026-50139, GHSA-j48m-h7xq-2xpj
Record: https://patchnext.com/advisories/cve-2026-50139 (revision 1, source checked 26 Oct 2026, 15:24 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: goshs.de/goshs/v2 2.1.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go goshs.de/goshs/v2: affected <= 2.0.9; fixed in 2.1.0

## Suggested inspection (read-only)
- Go goshs.de/goshs/v2: 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 goshs.de/goshs/v2.
- 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://github.com/advisories/GHSA-j48m-h7xq-2xpj (GitHub-reviewed advisory GHSA-j48m-h7xq-2xpj lists affected ranges: Go goshs.de/goshs/v2 >=0 <=2.0.9)

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