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CVE-2020-35863

31
FAUCET Score

CVE-2020-35863 is a critical HTTP request smuggling vulnerability affecting the hyper crate for Rust, specifically versions prior to 0.12.34. This flaw allows for remote code execution in specific scenarios where an HTTP server is running on the loopback interface. With a CVSS score of 9.8 (Critical), it presents a high-impact threat, enabling full compromise of confidentiality, integrity, and availability without user interaction. While there is no evidence of active exploitation or publicly available exploit code in Metasploit, Nuclei, or ExploitDB, the vulnerability has garnered significant community discussion, indicating awareness and potential interest among researchers.

Impacted Technologies

VendorProductVersion(s)CPE
< 0.12.34CPE matchmatch criteria
cpe:2.3:a:hyper:hyper:*:*:*:*:*:rust:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.80%
Probability of exploitation in next 30 days
EPSS Percentile
85.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0280 is in the 76th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

rustpatch availablevia ghsa
Product: hyperFixed in: 0.12.34

Vendor Advisories (1)

rustGHSA-h3qr-rq2j-74w4critical

HTTP Request Smuggling in hyper

Aug 25, 2021

References

rustsec.org / advisories/RUSTSEC-2020-0008.html
PatchThird Party Advisory