The R09 scholarly hardening routes every hop through check_outbound_url with
block_private=True. On a DNS64/NAT64 network, an IPv4-only host can resolve
through the RFC 6052 Well-Known Prefix. For example, export.arxiv.org resolved
to 64:ff9b::924b:5b2a in the reproduced environment.
CPython classifies that outer IPv6 prefix as reserved, so the URL guard rejected
the request before examining the effective IPv4 destination.
Decode addresses in exactly 64:ff9b::/96 to their embedded IPv4 destination and
evaluate that destination under the strict outbound policy.
The translated target is always checked with private-address blocking enabled.
This prevents the NAT64 prefix from becoming a path to loopback, private,
shared/CGNAT, link-local, multicast, unspecified, or other non-global IPv4
space.
Network-specific translation prefixes are not decoded. In particular,
64:ff9b:1::/48 remains subject to the existing IPv6 policy.
Coverage includes:
- public IPv4 destinations embedded through the RFC 6052 prefix
- loopback, link-local, private, CGNAT, multicast, unspecified, benchmark, and
TEST-NET rejection
- network-specific NAT64 prefixes remaining undecoded
- deterministic scholarly provider tests without live DNS dependence
- redirect query parameter isolation
- relative redirect resolution
- HTTP error fallback behavior
- editor draft GET and DELETE behavior remaining unaffected
R09, R11, and R01 were independently audited and otherwise left unchanged.
* security(url-safety): reject RFC 6598 shared address space in strict mode
Strict mode (block_private=True) is a full SSRF lockdown, but it only
rejected is_private and is_loopback targets. CPython does not classify RFC
6598 shared/CGNAT space (100.64.0.0/10) as is_private (it is "shared", not
"private"), so a public redirect into 100.64.0.1 passed the per-hop guard
and still issued the request to a potentially internal CGNAT service.
not is_global would also exclude it, but only on CPython 3.11.10+/3.12.4+/
3.13+; the CI matrix runs 3.11/3.12, so reject the range explicitly to stay
correct across patch levels and the 3.14 runtime image. Default local-first
mode is unchanged. Adds strict-mode coverage for shared, non-global, and
public targets.
* docs(url-safety): correct CGNAT is_global rationale in strict-mode comment
The prior comment claimed `not is_global` catches 100.64.0.0/10 only on
CPython 3.11.10+/3.12.4+/3.13+. That is inaccurate for CGNAT: is_global
is False for 100.64.0.1 on every supported version (verified 3.10-3.14).
The version-fragility applies to other ranges gh-113171 touched, not CGNAT.
The explicit range reject is still the right choice; restate the reason as
is_private not covering shared space, and not coupling strict mode to
is_global's broader, cross-version definition. No behavior change.
POST /api/embeddings/endpoint takes a user-supplied URL and immediately
makes an outbound httpx request to it with no validation. The admin gate
added earlier (PR #80) closed the unauthenticated-access part of #132; this
addresses the remaining request: validate the URL before fetching it.
Odysseus is local-first, so pointing the embedding endpoint at a loopback or
LAN server (local vLLM / llama.cpp / Ollama) is a normal setup — a blanket
private-IP block would break the primary use case. So the guard:
- always rejects non-HTTP(S) schemes (file://, gopher://, ftp:// …),
- always rejects the link-local range (169.254.0.0/16, incl. the cloud
instance-metadata 169.254.169.254 exfil vector) plus multicast /
reserved / unspecified, and IPv4-mapped-IPv6 forms of the above,
- keeps loopback/LAN allowed by default, and
- adds EMBEDDING_BLOCK_PRIVATE_IPS=true for full SSRF lockdown on exposed
multi-tenant deployments.
Logic lives in src/url_safety.py (stdlib only, resolver injectable) so it is
unit-testable without real DNS; the route calls it before the health-check
request. Covered by tests/test_url_safety.py (8 cases).
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Alexandre Teixeira