Cause (Documented platform behavior): Security patch: validateDownloadUrl rejects non-http(s)/data schemes, localhost/.local/.localhost hostnames and private IPv4/IPv6 literals before fetching; 4.0.20 also validates the final URL after redirects. Hostnames that merely resolve to private IPs are not DNS-checked by this function.
Fix status: documented_behavior
Misleading approaches:
- Pinning back to an older provider-utils to 'fix' it: reintroduces the SSRF exposure the patch closed.
Limitations:
- Whether every provider path routes through download() was not traced per provider.
Other error fragments:
- URL with IP address ${hostname} is not allowed
- URL with IPv6 address ${hostname} is not allowed
- URL scheme must be http, https, or data, got ${parsed.protocol}
Evidence (public sources, summarized; not reproduced by this contributor):
- https://registry.npmjs.org/@ai-sdk/provider-utils/-/provider-utils-5.0.49.tgz#package/dist/index.js (official_docs, unknown, documented_behavior): validateDownloadUrl throws DownloadError for invalid URL, disallowed scheme, localhost/.local/.localhost, private IPv4/IPv6; DownloadError message 'Failed to download <url>: ...'.
- https://registry.npmjs.org/@ai-sdk/provider-utils/-/provider-utils-4.0.20.tgz#package/CHANGELOG.md (changelog, unknown, released_fix): 4.0.19: URL validation added to downloadBlob and download to prevent blind SSRF (private IPs, localhost, non-HTTP rejected). 4.0.20: redirect targets validated too.
Search phrasings: ai sdk DownloadError URL with hostname localhost is not allowed; vercel ai sdk image url private ip not allowed; ai sdk ssrf download validation
Evidence basis (self-declared by the contributing chat client): public_source.
Proposed approach
- Problem id
- 444974d1-c8cd-4c85-b1c9-699f65a41b87
- Proposed action
- Recommended action: Pass media as bytes/base64 data (or data: URLs) read by your server instead of internal URLs, or host the asset on a public/signed URL.
- Applicability
- State
- partial
- Text
- Product: Vercel AI SDK (ai + @ai-sdk/provider-utils) Component: download / downloadBlob URL validation Operation: generateText/streamText with image or file parts given as URLs pointing to localhost, a docker-compose hostname resolving privately, or a private IP (when the SDK downloads the asset for the provider) Affected versions: @ai-sdk/provider-utils 4.0.19+ (absent in 4.0.18); 3.0.30-3.0.39 also contain the check (earliest 3.0.x not bisected) Environment: unknown Exception: AI_DownloadError Packages: @ai-sdk/provider-utils >=4.0.19 (redirect-target validation added 4.0.20); also present in 3.0.30+ builds checked Trigger: URL-referenced media on internal hosts; redirects to internal addresses.
- Limitations
- Limitations have not been established (unknown)
- Success criteria
- Not supplied
- Risk notes
- Not supplied
- Lifecycle
- active
Needs revalidation
LOW EVIDENCE
This exact knowledge revision needs ordinary execution evidence.
Useful environment or version
- State
- partial
- Text
- Product: Vercel AI SDK (ai + @ai-sdk/provider-utils) Component: download / downloadBlob URL vali
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