yopass Prometheus metrics middleware allows remote memory exhaustion through unbounded method labels

Exploitation

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

CVSS

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

EPSS

• CVE-2026-107840: 0.44% estimated exploitation activity in the next 30 days; percentile 38.71 (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.

The Prometheus metrics middleware in pkg/server/server.go used r.Method directly as a label value on request counter and duration histogram metrics. Since the mux catch-all route matches any HTTP method, an unauthenticated attacker can send requests with arbitrary method strings (e.g. curl -X "M1" http://host/), each creating new counter and histogram time series in the Prometheus registry. The registry's internal maps never evict entries. An attacker issuing requests with unique method values causes monotonic memory growth until the process is OOM-killed. Additionally, /metrics scrape latency degrades proportionally, eventually timing out and blinding monitoring. Remediation: Upgrade to 14.7.0 or later, which clamps the method label to a fixed allowlist (GET, POST, PUT, DELETE, OPTIONS, HEAD, CONNECT, TRACE) and maps everything else to other.

Published by the source

9 Oct 2026, 20:42 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-6r69-c6wg-7g8m

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GO-2026-6720

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-6r69-c6wg-7g8m

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# Patch Next advisory brief: CVE-2026-107840

Advisory: yopass Prometheus metrics middleware allows remote memory exhaustion through unbounded method labels
IDs: CVE-2026-107840, GHSA-6r69-c6wg-7g8m
Record: https://patchnext.com/advisories/cve-2026-107840 (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 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/jhaals/yopass 0.0.0-20260727191436-61e31ead04a4. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/jhaals/yopass: affected < 0.0.0-20260727191436-61e31ead04a4; fixed in 0.0.0-20260727191436-61e31ead04a4

## Suggested inspection (read-only)
- Go github.com/jhaals/yopass: 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/jhaals/yopass.
- 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-2026-6720 (OSV record GO-2026-6720 lists affected ranges: Go github.com/jhaals/yopass >=0 <0.0.0-20260727191436-61e31ead04a4 (fixed))
- Verified: https://osv.dev/vulnerability/GHSA-6r69-c6wg-7g8m (OSV record GHSA-6r69-c6wg-7g8m lists affected ranges: Go github.com/jhaals/yopass >=0 <0.0.0-20260727191436-61e31ead04a4 (fixed))
- Verified: https://github.com/advisories/GHSA-6r69-c6wg-7g8m (GitHub-reviewed advisory GHSA-6r69-c6wg-7g8m lists affected ranges: Go github.com/jhaals/yopass >=0 <0.0.0-20260727191436-61e31ead04a4)

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