pyLoad: SSRF guard bypass via IPv6 6to4/NAT64 transition wrappers of internal IPs

Exploitation

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

CVSS

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

EPSS

• CVE-2026-48737: 0.29% estimated exploitation activity in the next 30 days; percentile 21.53 (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 isglobaladdress in src/pyload/core/utils/web/check.py is the central guard against SSRF-style outbound connections in pyload-ng. It tests whether a given IP is "globally routable" via Python's ipaddress.ipaddress(value).isglobal, and callers treat not isglobal as "deny": Python's ipaddress.IPv6Address.isglobal classifies the NAT64 well-known prefix as globally routable on every supported Python version (3.9 through 3.14 confirmed), and on older Pythons (3.9-3.11) the 6to4 prefix as well: | address | isglobal on Py 3.9-3.11 | isglobal on Py 3.12+ | wrapped IPv4 | |----------------------------------|---------------------------|--------------------------|----------------------| | 2002:7f00:0001:: (6to4) | True | False | 127.0.0.1 | | 2002:0a00:0001:: (6to4) | True | False | 10.0.0.1 | | 2002:a9fe:a9fe:: (6to4) | True | False | 169.254.169.254 (IMDS)| | 64:ff9b::a9fe:a9fe (NAT64) | True | True | 169.254.169.254 | | 64:ff9b::7f00:1 (NAT64) | True | True | 127.0.0.1 | pyload-ng…

Published by the source

9 Jul 2026, 13:35 UTC

Last modified by the source

13 Jul 2026, 16:42 UTC

Source last checked

26 Oct 2026, 13:46 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-m5x5-28jr-gpjj

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-m5x5-28jr-gpjj

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# Patch Next advisory brief: CVE-2026-48737

Advisory: pyLoad: SSRF guard bypass via IPv6 6to4/NAT64 transition wrappers of internal IPs
IDs: CVE-2026-48737, GHSA-m5x5-28jr-gpjj
Record: https://patchnext.com/advisories/cve-2026-48737 (revision 2, source checked 26 Oct 2026, 13:46 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.9)
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
- PyPI pyload-ng: affected <= 0.5.0b3.dev100

## Suggested inspection (read-only)
- `python -m pip show pyload-ng`: prints the installed version. Run with the environment that serves production active.

## 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 pyload-ng.
- 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-m5x5-28jr-gpjj (OSV record GHSA-m5x5-28jr-gpjj lists affected ranges: PyPI pyload-ng >=0 <=0.5.0b3.dev100)
- Verified: https://github.com/advisories/GHSA-m5x5-28jr-gpjj (GitHub-reviewed advisory GHSA-m5x5-28jr-gpjj lists affected ranges: PyPI pyload-ng >=0 <=0.5.0b3.dev100)

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