How severe is CVE-2020-25613?

CVE-2020-25613 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2020-25613?

CVE-2020-25613 affects the following packages: webrick (RubyGems), webrick (RubyGems), webrick (RubyGems). Ecosystems affected: RubyGems.

How do I fix CVE-2020-25613?

Update webrick to 1.6.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-25613 is resolved across your whole dependency graph.

How do I detect CVE-2020-25613 in my RubyGems dependencies?

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

How do I mitigate CVE-2020-25613 if there is no patch (or I can't update yet)?

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.

Is CVE-2020-25613 actively exploited in the wild?

No public exploit code has been indexed for CVE-2020-25613 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2020-25613?

CVE-2020-25613 has an EPSS (Exploit Prediction Scoring System) score of 3.8%, placing it in the 90th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2020-25613?

CVE-2020-25613 is classified as CWE-444 (CWE-444). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2020-25613 published, and has it been updated?

CVE-2020-25613 was published on October 6, 2020 and was last updated on October 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💎

💎 RubyGems

Not in CISA KEV

HIGH severity

CVE-2020-25613 — webrick

HIGHFix: ruby/webrick@8946bb3

CVE-2020-25613 is a high-severity (CVSS 7.5) CWE-444 vulnerability in webrick. A fix is available for webrick — see the affected versions and patch details below.

WEBRick vulnerable to HTTP Request/Response Smuggling

Also known asBIT-ruby-2020-25613BIT-ruby-min-2020-25613GHSA-gwfg-cqmg-cf8f

Published

Oct 6, 2020

Updated

Oct 24, 2026

Affected

3 pkgs

Patched

3 / 3

Exploits

None indexed

Exploitation data as of Nov 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

3.8%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs90th percentile — riskier than 90% of all scored CVEsHighest risk

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

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

3 pkgs affected

💎webrick💎webrick💎webrick

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

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.

Affected Packages

3 total 3 fixed

Ecosystem	Package	Vulnerable range	Fix
💎RubyGems	`webrick`	≥ 1.6.0&&< 1.6.1	1.6.1`bundle update webrick --conservative`
💎RubyGems	`webrick`	≥ 1.5.0&&< 1.5.1	1.5.1`bundle update webrick --conservative`
💎RubyGems	`webrick`	all versions	1.4.4`bundle update webrick --conservative`

Affected Products

3 products · 6 configurations

fedorafedoraproject

2 versions

3233

Application

rubyruby-lang

≥ 2.7.0 && ≤ 2.7.1

range

Application

webrickruby-lang

≤ 1.6.0

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for webrick, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update webrick to 1.6.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-25613 is resolved across your whole dependency graph.
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.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Product	Fixed in	Advisory
Red Hat Enterprise Linux 8	`ruby:2.7-8040020210421133318.522a0ee4`	RHSA-2021:2584
Red Hat Enterprise Linux 8	`ruby:2.5-8040020200923213910.522a0ee4`	RHSA-2021:2587
Red Hat Enterprise Linux 8	`ruby:2.6-8040020210430142949.522a0ee4`	RHSA-2021:2588
Red Hat Enterprise Linux 8.1 Update Services for SAP Solutions	`ruby:2.6-8010020220201152941.c27ad7f8`	RHSA-2022:0581
Red Hat Enterprise Linux 8.2 Extended Update Support	`ruby:2.6-8020020220201131207.4cda2c84`	RHSA-2022:0582
Red Hat Software Collections for Red Hat Enterprise Linux 7	`rh-ruby25-ruby-0:2.5.9-9.el7`	RHSA-2021:2104
Red Hat Software Collections for Red Hat Enterprise Linux 7	`rh-ruby27-ruby-0:2.7.3-129.el7`	RHSA-2021:2229
Red Hat Software Collections for Red Hat Enterprise Linux 7	`rh-ruby26-ruby-0:2.6.7-119.el7`	RHSA-2021:2230

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2020-25613 in your dependencies?

Find it across RubyGems, including transitive dependencies.

Scan my dependencies How O3 SCA works