WEBRick vulnerable to HTTP Request/Response Smuggling

Description

An issue was discovered in Ruby through 2.5.8, 2.6.x through 2.6.6, and 2.7.x through 2.7.1. WEBrick, a simple HTTP server bundled with Ruby, had not checked the transfer-encoding header value rigorously. An attacker may potentially exploit this issue to bypass a reverse proxy (which also has a poor header check), which may lead to an HTTP Request Smuggling attack.

Basic information

Type
reviewed
Severity
high
Advisory on GitHub
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Repository advisory
Source code
Browse source ↗
Published (advisory)
2022-05-24 17:30:10 UTC
Updated
2025-05-30 16:06:10 UTC
GitHub reviewed
2023-03-08 19:59:16 UTC
NVD published
2020-10-06

EPSS Score

Score Percentile
0.27% 50.54%

CVSS Scores

Base score Version Severity Vector
7.5 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.

Identifiers

CWEs

CWE id Name
CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

Credits

  • decsecre583 (analyst)

Affected packages (3)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
rubygems webrick = 1.6.0 1.6.1
rubygems webrick = 1.5.0 1.5.1
rubygems webrick < 1.4.4 1.4.4

References

cvelogic Threat Intelligence