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MEDIUM severity

CVE-2017-18587 — hyper

MEDIUM

CVE-2017-18587 is a medium-severity (CVSS 5.3) CWE-93 vulnerability in hyper. A fix is available for hyper — see the affected versions and patch details below.

Headers containing newline characters can split messages in hyper

Also known asGHSA-q89x-f52w-6hj2RUSTSEC-2017-0002
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Oct 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.0%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs63th percentile — riskier than 63% of all scored CVEsHighest risk
0.00%0.51%1.02%1.53%0.2%1.0%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2017-18587 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

2 pkgs affected
🦀hyper🦀hyper

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.

Description

Serializing of headers to the socket did not filter the values for newline bytes (\r or \n), which allowed for header values to split a request or response. People would not likely include newlines in the headers in their own applications, so the way for most people to exploit this is if an application constructs headers based on unsanitized user input.

This issue was fixed by replacing all newline characters with a space during serialization of a header value.

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
🦀crates.iohyper≥ 0.10.0&&< 0.10.20.10.2cargo update -p hyper --precise 0.10.2
🦀crates.iohyperall versions0.9.18cargo update -p hyper --precise 0.9.18

Affected Products

1 product · 2 configurations
Application
hyperhyper
≥ 0.10.0 && < 0.10.2
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for hyper, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update hyper to 0.10.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2017-18587 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

Serializing of headers to the socket did not filter the values for newline bytes (\r or \n), which allowed for header values to split a request or response. People would not likely include newlines in the headers in their own applications, so the way for most people to exploit this is if an application constructs headers based on unsanitized user input. This issue was fixed by replacing all newline characters with a space during serialization of a header value.
O3 Security · Impact-Aware SCA

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CVE-2017-18587: hyper — Fixed in 0.10.2