CVE-2021-212994.8MediumCWE-444

CVE-2021-21299: Multiple Transfer-Encoding headers misinterprets request payload

hyperium · hyper

Affected: hyperium · Exploitation: possible (1 to 10%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

4.8%probability of exploitation in the next 30 days

92nd percentile

050100

Higher than 92% of scored CVEs

4.8MediumCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

hyper is an open-source HTTP library for Rust (crates.io). In hyper from version 0.12.0 and before versions 0.13.10 and 0.14.3 there is a vulnerability that can enable a request smuggling attack. The HTTP server code had a flaw that incorrectly understands some requests with multiple transfer-encoding headers to have a chunked payload, when it should have been rejected as illegal. This combined with an upstream HTTP proxy that understands the request payload boundary differently can result in "request smuggling" or "desync attacks". To determine if vulnerable, all these things must be true: 1) Using hyper as an HTTP server (the client is not affected), 2) Using HTTP/1.1 (HTTP/2 does not use transfer-encoding), 3) Using a vulnerable HTTP proxy upstream to hyper. If an upstream proxy correctly rejects the illegal transfer-encoding headers, the desync attack cannot succeed. If there is no proxy upstream of hyper, hyper cannot start the desync attack, as the client will repair the headers before forwarding. This is fixed in versions 0.14.3 and 0.13.10. As a workaround one can take the following options: 1) Reject requests that contain a `transfer-encoding` header, 2) Ensure any upstream proxy handles `transfer-encoding` correctly.

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

hyperium · hyper< 0.13.10; >= 0.14.0, < 0.14.3

On the Atlas

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Open the Atlas

Exploitation: Possible (1 to 10%). EPSS between 1% and 10%.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Inconsistent Interpretation of HTTP Requests · Injection and Smuggling
Published: February 2021
Band: Possible (1 to 10%), February 2021

CoverageNo articles yet

No CyberSIXT article names CVE-2021-21299 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.