free5GC AMF: Missing default case in Content-Type switch in HTTPUEContextTransfer

Exploitation

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

CVSS 4.0

5.5 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P · score source

EPSS

• CVE-2026-41136: 0.28% estimated exploitation activity in the next 30 days; percentile 20.81 (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 The HTTPUEContextTransfer handler in internal/sbi/apicommunication.go does not include a default case in the Content-Type switch statement. When a request arrives with an unsupported Content-Type, the deserialization step is silently skipped, err remains nil, and the processor is invoked with a completely uninitialized UeContextTransferRequest object. Details In internal/sbi/apicommunication.go, the HTTPUEContextTransfer function handles the Content-Type header with a switch statement that only covers application/json and multipart/related: This is inconsistent with the two analogous handlers in the same file, HTTPCreateUEContext and HTTPN1N2MessageTransfer, which both correctly include a default branch: The fix is simply to add the same default case to HTTPUEContextTransfer. PoC With a free5GC deployment running, send a POST request to the UE context transfer endpoint using any unsupported Content-Type (e.g. text/plain): Expected (correct) behavior: 400 Bad Request from the…

Published by the source

22 Apr 2026, 19:54 UTC

Last modified by the source

27 Apr 2026, 16:34 UTC

Source last checked

26 Oct 2026, 15:19 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-r99v-75p9-xqm5

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# Patch Next advisory brief: CVE-2026-41136

Advisory: free5GC AMF: Missing default case in Content-Type switch in HTTPUEContextTransfer
IDs: CVE-2026-41136, GHSA-r99v-75p9-xqm5
Record: https://patchnext.com/advisories/cve-2026-41136 (revision 1, source checked 26 Oct 2026, 15:19 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/free5gc/amf: affected <= 1.4.3

## Suggested inspection (read-only)
- Go github.com/free5gc/amf: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/free5gc/amf.
- 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-r99v-75p9-xqm5 (GitHub-reviewed advisory GHSA-r99v-75p9-xqm5 lists affected ranges: Go github.com/free5gc/amf >=0 <=1.4.3)

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