vulnerability / NVI-00012929 / Revision 1
urllib3: HTTPResponse.stream()/read_chunked() buffers an unbounded chunk-size line into memory
GitHub lists this reviewed advisory for urllib3. 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.
urllib3
source listed>= 1.10.3, < 2.8.0
## Impact urllib3's streaming API is designed for efficiently handling large HTTP responses by reading the content in chunks, rather than loading the entire response body into memory at once. When decoding a chunked-transfer-encoded response, this API reads each chunk's size field by buffering until it sees `\n` or EOF. A malicious HTTP server can return `Transfer-Encoding: chunked` and then send a very long run of bytes without any newline, causing the streaming client to buffer that entire run before urllib3 can reject the chunk size as invalid and allocate more memory than intended. To fix the issue, we'll reject chunk-size fields larger than 65536 bytes, as already done in the non-streaming case, which is currently handled by the Python standard library. Note that this only applies to reading the chunk-size field, not the chunk data, which is already handled correctly. Thus, there shouldn't be any impact for non-malicious servers. ## Affected usages Applications and libraries using urllib3 versions earlier than 2.8.0 may be affected whe
03 / Response
What to do next
- investigate
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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-vxq7-64xx-v4gw ↗
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- Revision 1 ·
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