← Vulnerability feed

Vulnerability record · CVE-2021-41816 · published 6 February 2022

CVE-2021-41816: Ruby-lang cgi integer overflow vulnerability

Ruby Lang · Cgi

CGI.escape_html in Ruby before 2.7.5 and 3.x before 3.0.3 has an integer overflow and resultant buffer overflow via a long string on platforms (such as Windows) where size_t and long have different numbers of bytes. This also affects the CGI gem before 0.3.1 for Ruby.

9.8 CVSS 3.1 Critical EPSS 4.8% · top 8.4% CWE-190 · Integer overflow
9.8CVSS 3.1 base score, v2 7.5
4.8%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
14References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

CGI.escape_html in Ruby before 2.7.5 and 3.x before 3.0.3 has an integer overflow and resultant buffer overflow via a long string on platforms (such as Windows) where size_t and long have different numbers of bytes. This also affects the CGI gem before 0.3.1 for Ruby.

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

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://hackerone.com/reports/1328463 Permissions RequiredThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IUXQCH6FRKANCVZO2Q7D2SQ
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UTOJGS5IEFDK3UOO7IY4OTT
https://security-tracker.debian.org/tracker/CVE-2021-41816 Third Party Advisory
https://security.gentoo.org/glsa/202401-27
https://security.netapp.com/advisory/ntap-20220303-0006/ Third Party Advisory
https://www.ruby-lang.org/en/news/2021/11/24/buffer-overrun-in-cgi-escape_html-cve-2021-41816/ ExploitVendor Advisory
https://hackerone.com/reports/1328463 Permissions RequiredThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IUXQCH6FRKANCVZO2Q7D2SQ
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UTOJGS5IEFDK3UOO7IY4OTT
https://security-tracker.debian.org/tracker/CVE-2021-41816 Third Party Advisory
https://security.gentoo.org/glsa/202401-27
https://security.netapp.com/advisory/ntap-20220303-0006/ Third Party Advisory
https://www.ruby-lang.org/en/news/2021/11/24/buffer-overrun-in-cgi-escape_html-cve-2021-41816/ ExploitVendor Advisory

Track CVE-2021-41816 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

10.0CVE-2021-44228Apache Log4j2 JNDI lookup remote code executionApache Log4j2 versions 2.0-beta9 through 2.15.0 (excluding 2.12.2, 2.12.3, and 2.3.1) do not protect against attacker-controlled LDAP and other JNDI …KEVEPSS 100%analysed9.8CVE-2024-4577PHP-CGI on Windows argument injection leads to remote code executionPHP-CGI on Windows can misinterpret characters in the command line passed to Win32 API functions when certain code pages are configured, due to Windo…KEVEPSS 100%analysed9.8CVE-2021-44026Roundcube Webmail SQL injection via search parametersRoundcube Webmail before 1.3.17 and 1.4.x before 1.4.12 is prone to SQL injection through the search or search_params input. The flaw is remotely rea…KEVEPSS 70%analysed9.8CVE-2021-42013Apache HTTP Server path traversal and RCE via incomplete fixThe fix for CVE-2021-41773 in Apache HTTP Server 2.4.50 was insufficient, leaving a path traversal flaw that lets attackers map URLs to files outside…KEVEPSS 100%analysed9.8CVE-2021-41773Apache HTTP Server 2.4.49 path traversal and RCEA path normalization flaw introduced in Apache HTTP Server 2.4.49 lets attackers map URLs to files outside directories configured by Alias-like direc…KEVEPSS 100%analysed9.8CVE-2021-1870Apple WebKit logic flaw allows remote code executionA logic issue in Apple's WebKit was addressed with improved restrictions, affecting macOS Big Sur, Catalina, Mojave, iOS and iPadOS, plus WebKitGTK a…KEVEPSS 7.7%analysed9.8CVE-2021-1871Apple WebKit logic flaw allows remote code executionA logic issue in Apple's WebKit was addressed with improved restrictions. It affects macOS Big Sur, Catalina, Mojave, iOS and iPadOS, and a remote at…KEVEPSS 7.0%analysed9.8CVE-2020-16846SaltStack Salt API shell injection via crafted web requestsSaltStack Salt through 3002 is vulnerable to OS command injection when the SSH client is enabled and crafted web requests are sent to the Salt API. T…KEVEPSS 100%analysed

Source: NIST National Vulnerability Database (record CVE-2021-41816), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.