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Not in CISA KEV
MEDIUM severity

GHSA-xrr9-rh8p-433v

MEDIUMFix: ktorio/ktor#1547

GHSA-xrr9-rh8p-433v is a medium-severity (CVSS 5.4) CWE-444 vulnerability in io.ktor:ktor-client-cio. O3 Security confirms whether GHSA-xrr9-rh8p-433v is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Request smuggling is possible when both chunked TE and content length specified

Also known asCVE-2020-5207
Published
Jan 27, 2020
Updated
Jul 8, 2026
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Jul 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Real-World Exposure

2 pkgs affected
io.ktor:ktor-client-cioio.ktor:ktor-server-cio

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

Description

Impact

Request smuggling is possible when running behind a proxy that doesn't handle Content-Length and Transfer-Encoding properly or doesn't handle alone \n as a headers separator.

Patches

https://github.com/ktorio/ktor/pull/1547

Workarounds

None except migrating to a better proxy.

References

https://portswigger.net/web-security/request-smuggling https://tools.ietf.org/html/rfc7230#section-9.5

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
Mavenio.ktor:ktor-client-cioall versions1.3.0
Mavenio.ktor:ktor-server-cioall versions1.3.0

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.ktor:ktor-client-cio. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update io.ktor:ktor-client-cio to 1.3.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xrr9-rh8p-433v 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.

  4. How O3 protects you

    O3 pinpoints whether GHSA-xrr9-rh8p-433v is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-xrr9-rh8p-433v. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Impact Request smuggling is possible when running behind a proxy that doesn't handle Content-Length and Transfer-Encoding properly or doesn't handle alone \n as a headers separator. ### Patches https://github.com/ktorio/ktor/pull/1547 ### Workarounds None except migrating to a better proxy. ### References https://portswigger.net/web-security/request-smuggling https://tools.ietf.org/html/rfc7230#section-9.5
O3 Security · Impact-Aware SCA

Is GHSA-xrr9-rh8p-433v in your dependencies?

O3 detects GHSA-xrr9-rh8p-433v across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.