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.
CVE-2020-25613
This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 3.8%, top 11% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- High severity, but no confirmed exploitation yet
A fix is available — apply it.
- CVSS v3
- 7.5
- EG Score
- 7.5(medium)
- EG Risk
- —
- EPSS
- 89.0%
- KEV
- Not listed
Published
October 6, 2020
Last Modified
November 21, 2024
References (16)
- cve@mitrehttps://github.com/ruby/webrick/commit/8946bb38b4d87549f0d99ed73c62c41933f97cc7
- cve@mitrehttps://hackerone.com/reports/965267
- cve@mitrehttps://lists.debian.org/debian-lts-announce/2023/04/msg00033.html
- cve@mitrehttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PFP3E7KXXT3H3KA6CBZPUOGA5VPFARRJ/
- cve@mitrehttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/YTZURYROG3FFED3TYCQOBV66BS4K6WOV/
- cve@mitrehttps://security.gentoo.org/glsa/202401-27
- cve@mitrehttps://security.netapp.com/advisory/ntap-20210115-0008/
- cve@mitrehttps://www.ruby-lang.org/en/news/2020/09/29/http-request-smuggling-cve-2020-25613/
- af854a3a-2127-422b-91ae-364da2661108https://github.com/ruby/webrick/commit/8946bb38b4d87549f0d99ed73c62c41933f97cc7
- af854a3a-2127-422b-91ae-364da2661108https://hackerone.com/reports/965267
- af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2023/04/msg00033.html
- af854a3a-2127-422b-91ae-364da2661108https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PFP3E7KXXT3H3KA6CBZPUOGA5VPFARRJ/
- af854a3a-2127-422b-91ae-364da2661108https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/YTZURYROG3FFED3TYCQOBV66BS4K6WOV/
- af854a3a-2127-422b-91ae-364da2661108https://security.gentoo.org/glsa/202401-27
- af854a3a-2127-422b-91ae-364da2661108https://security.netapp.com/advisory/ntap-20210115-0008/
Vendor Advisories for CVE-2020-25613(9)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- RHSA-2026:8838Red Hat Product SecurityMedium
Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update
- RHSA-2026:7307Red Hat Product SecurityMedium
Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update
- RHSA-2026:7305Red Hat Product SecurityMedium
Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update
- RHSA-2022:0582Red Hat Product SecurityHigh
Red Hat Security Advisory: ruby:2.6 security update
- RHSA-2022:0581Red Hat Product SecurityHigh
Red Hat Security Advisory: ruby:2.6 security update
- RHSA-2021:2587Red Hat Product SecurityMedium
Red Hat Security Advisory: ruby:2.5 security, bug fix, and enhancement update
- RHSA-2021:2588Red Hat Product SecurityMedium
Red Hat Security Advisory: ruby:2.6 security, bug fix, and enhancement update
- RHSA-2021:2230Red Hat Product SecurityMedium
Red Hat Security Advisory: rh-ruby26-ruby security, bug fix, and enhancement update
- +1 more
Patch Availability(12)
| Vendor / Ecosystem | Fixed in / Patch | Released | Source |
|---|---|---|---|
| ubuntu | ruby2.3-tcltk (2.3.1-2~ubuntu16.04.15) @ xenial | 2026-05-23 | ubuntu |
| redhat | ruby4-0-main-4.0.0-33.3.hum1 | 2026-04-17 | redhat |
| redhat | ruby3-4-main-3.4.8-31.1.hum1 | 2026-04-09 | redhat |
| redhat | ruby3-3-main-3.3.10-23.1.hum1 | 2026-04-09 | redhat |
| redhat | ruby:2.6-8010020220201152941.c27ad7f8 | 2022-02-21 | redhat |
| redhat | ruby:2.6-8020020220201131207.4cda2c84 | 2022-02-21 | redhat |
| redhat | ruby:2.7-8040020210421133318.522a0ee4 | 2021-06-29 | redhat |
| redhat | ruby:2.5-8040020200923213910.522a0ee4 | 2021-06-29 | redhat |
| redhat | ruby:2.6-8040020210430142949.522a0ee4 | 2021-06-29 | redhat |
| redhat | rh-ruby26-ruby-0:2.6.7-119.el7 | 2021-06-03 | redhat |
| redhat | rh-ruby27-ruby-0:2.7.3-129.el7 | 2021-06-03 | redhat |
| redhat | rh-ruby25-ruby-0:2.5.9-9.el7 | 2021-05-26 | redhat |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(1 across 1 ecosystem)
RubyGems(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| webrick | 1.3.1 ... 1.4.3 (6 versions) | 1.4.4 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Additional Vendor Advisories
(4)
Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.
- Microsoft MSRCCVE-2020-256132020-10-21
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.
- Red HatRHSA-2021:2229MODERATE2020-09-29
RHSA-2021:2229 — Moderate
- Red HatRHSA-2021:2584MODERATE2020-09-29
RHSA-2021:2584 — Moderate
- UbuntuUSN-4882-1LOW
Ruby vulnerabilities
Data Freshness Timeline
(refreshed 11× in last 7d / 43× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-22 22:37 UTCEG score recompute
- 2026-07-22 14:05 UTCEPSS rescore
- 2026-07-21 15:22 UTCEPSS rescore
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- 2026-07-13 01:38 UTCOSV refresh
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- 2026-06-24 11:20 UTCOSV refresh
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- 2026-06-07 15:39 UTCOSV refresh
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- 2026-05-24 16:48 UTCEPSS rescore
- 2026-05-23 07:00 UTCEG score recompute
- 2026-05-23 07:00 UTCVendor advisory
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Frequently asked(5)
What is CVE-2020-25613?
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What is the CVSS score of CVE-2020-25613?
How do I remediate CVE-2020-25613?
Dependency Blast Radius
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