GHSA-C9HR-64H3-GXPC

Vulnerability from github – Published: 2026-07-30 14:48 – Updated: 2026-07-30 14:48
VLAI
Summary
Flyto2 Core: Guarded HTTP modules follow redirects into internal space without per-hop SSRF revalidation
Details

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://<cloud-metadata-ip>/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).

Severity
8.5 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 2.26.6"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "flyto-core"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.26.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-67424"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-30T14:48:16Z",
    "nvd_published_at": "2026-07-29T19:16:51Z",
    "severity": "HIGH"
  },
  "details": "## Summary\nThe 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\u0027s 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.\n\n## Root Cause\n`src/core/modules/atomic/http/get.py:116` calls `session.get(url, ...)` with no `allow_redirects` argument \u2192 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 \u2014 there is no redirect interception or Location revalidation.\n\n## Impact\nFull readable SSRF that defeats the primary SSRF control on the very modules that correctly validate. Confidentiality of internal/metadata responses (C:H), S:C.\n\n## Proof of Concept\nVerified 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`.\n```\nattacker hosts http://attacker.tld/r  -\u003e  302 Location: http://\u003ccloud-metadata-ip\u003e/latest/meta-data/...\nexecute_module http.get {\"url\":\"http://attacker.tld/r\"}\n```\n\n## Attack Chain\n1. Entry: `execute_module http.get {url:\"http://attacker.tld/r\"}` (attacker 302-\u003einternal). Guard: `validate_url_with_env_config(url)` (get.py:104). Bypass proof: validation runs on `attacker.tld` (public) \u2192 passes; never re-run on the redirect target.\n2. Sink: `session.get(url)` (get.py:116) \u2014 no `allow_redirects` arg \u2192 aiohttp default True. Bypass proof: grep of `http/` for `on_request_redirect`/`response.history` \u2192 NONE.\n3. Impact: aiohttp follows 302 to the internal host; internal body returned (get.py:118).\n\n## Bypass Evidence\nLive 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.\n\n## Affected Versions\n`\u003c= 2.26.6` \u2014 `get.py:116`, `request.py:60`, `batch.py:57` present on latest release tag.\n\n## Suggested Fix\nSet `allow_redirects=False` and manually revalidate each `Location` header through `validate_url_with_env_config` before following, or cap and re-check every hop.\n\n## Credit\n\nVulnerability discovered by zx (Jace).",
  "id": "GHSA-c9hr-64h3-gxpc",
  "modified": "2026-07-30T14:48:17Z",
  "published": "2026-07-30T14:48:16Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/flytohub/flyto-core/security/advisories/GHSA-c9hr-64h3-gxpc"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-67424"
    },
    {
      "type": "WEB",
      "url": "https://github.com/flytohub/flyto-core/commit/0a0a528520ec18f5a21f1ddf858a71cc1edfb6e9"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/flytohub/flyto-core"
    },
    {
      "type": "WEB",
      "url": "https://github.com/flytohub/flyto-core/releases/tag/v2.26.7"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Flyto2 Core: Guarded HTTP modules follow redirects into internal space without per-hop SSRF revalidation"
}



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