vulnerability / NVI-00015341 / Revision 1
dssrf has an SSRF bypass with remove_at_symbol_in_string
GitHub lists this reviewed advisory for dssrf. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
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02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
dssrf
source listed<= 1.0.3
## Summary `is_url_safe` in v1.0.3 contains an SSRF bypass. `remove_at_symbol_in_string` is applied to the raw URL string **before** `new URL()` parses it. This strips the `@` that separates userinfo from host, corrupting the hostname so internal IPs are never checked. ## Vulnerability In `helpers.ts`, `is_url_safe` does: ```ts u = remove_at_symbol_in_string(u); // strips ALL '@' from the raw string // ... const parsed = new URL(u); const hostname = parsed.hostname; // resolved from the corrupted string ``` ### What happens step by step Input: `http://evil.com@127.0.0.1/` 1. `remove_at_symbol_in_string` → `http://evil.com127.0.0.1/` 2. `new URL(...)` → `hostname = "evil.com127.0.0.1"` 3. Not a bare IP, not IPv6 → passes all IP checks 4. `is_hostname_resolve_to_internal_ip("evil.com127.0.0.1")` → NXDOMAIN → returns false 5. **Result: `true` (safe)** — but any HTTP client using the *original* URL connects to `127.0.0.1` ### Proof of Concept ```js import nock from 'nock'; import { got } from 'got'; import { is_url_safe } from 'dssrf'; // Simulate an internal server at 10.0.0.1 that returns secret data nock('http://10.0.0.1:80').persist().get('/').reply(200, 'SECRET_DATA
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
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04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
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- GHSA-cg4g-m8jx-vjv2 ↗
GitHub Advisory Database · vendor advisory
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- Revision 1 ·
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