vulnerability / NVI-00018512 / Revision 1
NIOExtras: NIOHTTPRequestDecompressor ratio limit bypass via inflated Content-Length
GitHub lists this reviewed advisory for github.com/apple/swift-nio-extras. 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
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
github.com/apple/swift-nio-extras
source listed< 1.34.1
### Impact When `NIOHTTPRequestDecompressor` is configured with `.ratio(N)`, the decompression limit is enforced using the `Content-Length` header value from the incoming request rather than the actual number of compressed bytes received. Since `Content-Length` is attacker-controlled, a malicious client can supply an inflated value that causes the ratio check to always pass, effectively disabling the configured decompression limit. This allows an attacker to send a small, highly-compressed payload (a "gzip bomb") with a falsified `Content-Length` header to bypass the ratio-based protection entirely. The server will decompress the payload without limit, consuming unbounded memory and potentially causing denial of service. For example, a gzip payload containing highly repetitive data can achieve amplification ratios of several hundred to one. Under `.ratio(10)` such a payload should be rejected, but if the attacker sets `Content-Length` to match the decompressed size, the check evaluates `decompressed > decompressed * 10` which is always false, and the payload is accepted without error. Across repeated requests, this allows sustained memory amplification far exceeding the configu
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.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database
A fixed release is not deployment evidence.
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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-6ph5-fww6-vfwv ↗
GitHub Advisory Database · vendor advisory
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Public revision history
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- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.