CVE-2025-27219

In the CGI gem before 0.4.2 for Ruby, the CGI::Cookie.parse method in the CGI library contains a potential Denial of Service (DoS) vulnerability. The method does not impose any limit on the length of the raw cookie value it processes. This oversight can lead to excessive resource consumption when parsing extremely large cookies.

In the CGI gem before 0.4.2 for Ruby, the CGI::Cookie.parse method in the CGI library contains a potential Denial of Service (DoS) vulnerability. The method does not impose any limit on the length of the raw cookie value it processes. This oversight can lead to excessive resource consumption when parsing extremely large cookies.

In the CGI gem before 0.4.2 for Ruby, the CGI::Cookie.parse method in the CGI library contains a potential Denial of Service (DoS) vulnerability. The method does not impose any limit on the length of the raw cookie value it processes. This oversight can lead to excessive resource consumption when parsing extremely large cookies.

There is a possibility for DoS by in the cgi gem. This vulnerability has been assigned the CVE identifier CVE-2025-27219. We recommend upgrading the cgi gem.

Details

CGI::Cookie.parse took super-linear time to parse a cookie string in some cases. Feeding a maliciously crafted cookie string into the method could lead to a Denial of Service.

Please update CGI gem to version 0.3.5.1, 0.3.7, 0.4.2 or later.

Affected versions

cgi gem versions <= 0.3.5, 0.3.6, 0.4.0 and 0.4.1.

Credits

Thanks to lio346 for discovering this issue. Also thanks to mame for fixing this vulnerability.

Ruby is a fast and easy interpreted scripting language for object-oriented programming. It has many functions for processing text Files and perform system management tasks (such as Perl).

Security Fix(es):

In the CGI gem before 0.4.2 for Ruby, the CGI::Cookie.parse method in the CGI library contains a potential Denial of Service (DoS) vulnerability. The method does not impose any limit on the length of the raw cookie value it processes. This oversight can lead to excessive resource consumption when parsing extremely large cookies.(CVE-2025-27219)

In the CGI gem before 0.4.2 for Ruby, a Regular Expression Denial of Service (ReDoS) vulnerability exists in the Util#escapeElement method.(CVE-2025-27220)

In the URI gem before 1.0.3 for Ruby, the URI handling methods (URI.join, URI#merge, URI#+) have an inadvertent leakage of authentication credentials because userinfo is retained even after changing the host.(CVE-2025-27221)

Ruby is a fast and easy interpreted scripting language for object-oriented programming. It has many functions for processing text Files and perform system management tasks (such as Perl).

Security Fix(es):

In the CGI gem before 0.4.2 for Ruby, the CGI::Cookie.parse method in the CGI library contains a potential Denial of Service (DoS) vulnerability. The method does not impose any limit on the length of the raw cookie value it processes. This oversight can lead to excessive resource consumption when parsing extremely large cookies.(CVE-2025-27219)

In the CGI gem before 0.4.2 for Ruby, a Regular Expression Denial of Service (ReDoS) vulnerability exists in the Util#escapeElement method.(CVE-2025-27220)

In the URI gem before 1.0.3 for Ruby, the URI handling methods (URI.join, URI#merge, URI#+) have an inadvertent leakage of authentication credentials because userinfo is retained even after changing the host.(CVE-2025-27221)

Ruby is a fast and easy interpreted scripting language for object-oriented programming. It has many functions for processing text Files and perform system management tasks (such as Perl).

Security Fix(es):

In the CGI gem before 0.4.2 for Ruby, the CGI::Cookie.parse method in the CGI library contains a potential Denial of Service (DoS) vulnerability. The method does not impose any limit on the length of the raw cookie value it processes. This oversight can lead to excessive resource consumption when parsing extremely large cookies.(CVE-2025-27219)

In the CGI gem before 0.4.2 for Ruby, a Regular Expression Denial of Service (ReDoS) vulnerability exists in the Util#escapeElement method.(CVE-2025-27220)

In the URI gem before 1.0.3 for Ruby, the URI handling methods (URI.join, URI#merge, URI#+) have an inadvertent leakage of authentication credentials because userinfo is retained even after changing the host.(CVE-2025-27221)

Ruby is a fast and easy interpreted scripting language for object-oriented programming. It has many functions for processing text Files and perform system management tasks (such as Perl).

Security Fix(es):

In the CGI gem before 0.4.2 for Ruby, the CGI::Cookie.parse method in the CGI library contains a potential Denial of Service (DoS) vulnerability. The method does not impose any limit on the length of the raw cookie value it processes. This oversight can lead to excessive resource consumption when parsing extremely large cookies.(CVE-2025-27219)

In the CGI gem before 0.4.2 for Ruby, a Regular Expression Denial of Service (ReDoS) vulnerability exists in the Util#escapeElement method.(CVE-2025-27220)

In the URI gem before 1.0.3 for Ruby, the URI handling methods (URI.join, URI#merge, URI#+) have an inadvertent leakage of authentication credentials because userinfo is retained even after changing the host.(CVE-2025-27221)

Ruby is a fast and easy interpreted scripting language for object-oriented programming. It has many functions for processing text Files and perform system management tasks (such as Perl).

Security Fix(es):

In the CGI gem before 0.4.2 for Ruby, the CGI::Cookie.parse method in the CGI library contains a potential Denial of Service (DoS) vulnerability. The method does not impose any limit on the length of the raw cookie value it processes. This oversight can lead to excessive resource consumption when parsing extremely large cookies.(CVE-2025-27219)

In the CGI gem before 0.4.2 for Ruby, a Regular Expression Denial of Service (ReDoS) vulnerability exists in the Util#escapeElement method.(CVE-2025-27220)

In the URI gem before 1.0.3 for Ruby, the URI handling methods (URI.join, URI#merge, URI#+) have an inadvertent leakage of authentication credentials because userinfo is retained even after changing the host.(CVE-2025-27221)

Ruby is an extensible, interpreted, object-oriented, scripting language. It has features to process text files and to perform system management tasks.

Security Fix(es):

• net-imap: Net::IMAP vulnerable to possible DoS by memory exhaustion (CVE-2025-25186)

• CGI: Denial of Service in CGI::Cookie.parse (CVE-2025-27219)

• uri: userinfo leakage in URI#join, URI#merge and URI#+ (CVE-2025-27221)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Ruby is an extensible, interpreted, object-oriented, scripting language. It has features to process text files and to perform system management tasks.

Security Fix(es):

• rexml: DoS vulnerability in REXML (CVE-2024-39908)

• rexml: rubygem-rexml: DoS when parsing an XML having many specific characters such as whitespace character, >] and ]> (CVE-2024-41123)

• rexml: DoS vulnerability in REXML (CVE-2024-41946)

• rexml: DoS vulnerability in REXML (CVE-2024-43398)

• CGI: ReDoS in CGI::Util#escapeElement (CVE-2025-27220)

• CGI: Denial of Service in CGI::Cookie.parse (CVE-2025-27219)

• uri: userinfo leakage in URI#join, URI#merge and URI#+ (CVE-2025-27221)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Ruby is an extensible, interpreted, object-oriented, scripting language. It has features to process text files and to perform system management tasks.

Security Fix(es):

• CGI: ReDoS in CGI::Util#escapeElement (CVE-2025-27220)

• CGI: Denial of Service in CGI::Cookie.parse (CVE-2025-27219)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Ruby is an extensible, interpreted, object-oriented, scripting language. It has features to process text files and to perform system management tasks.

Security Fix(es):

• rexml: DoS vulnerability in REXML (CVE-2024-39908)

• rexml: rubygem-rexml: DoS when parsing an XML having many specific characters such as whitespace character, >] and ]> (CVE-2024-41123)

• rexml: DoS vulnerability in REXML (CVE-2024-41946)

• rexml: DoS vulnerability in REXML (CVE-2024-43398)

• CGI: ReDoS in CGI::Util#escapeElement (CVE-2025-27220)

• CGI: Denial of Service in CGI::Cookie.parse (CVE-2025-27219)

• uri: userinfo leakage in URI#join, URI#merge and URI#+ (CVE-2025-27221)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Ruby is an extensible, interpreted, object-oriented, scripting language. It has features to process text files and to perform system management tasks.

Security Fix(es):

• net-imap: Net::IMAP vulnerable to possible DoS by memory exhaustion (CVE-2025-25186)

• CGI: Denial of Service in CGI::Cookie.parse (CVE-2025-27219)

• uri: userinfo leakage in URI#join, URI#merge and URI#+ (CVE-2025-27221)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Ruby is an extensible, interpreted, object-oriented, scripting language. It has features to process text files and to perform system management tasks.

Security Fix(es):

• net-imap: Net::IMAP vulnerable to possible DoS by memory exhaustion (CVE-2025-25186)

• CGI: Denial of Service in CGI::Cookie.parse (CVE-2025-27219)

• uri: userinfo leakage in URI#join, URI#merge and URI#+ (CVE-2025-27221)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

In the CGI gem before 0.4.2 for Ruby, the CGI::Cookie.parse method in the CGI library contains a potential Denial of Service (DoS) vulnerability. The method does not impose any limit on the length of the raw cookie value it processes. This oversight can lead to excessive resource consumption when parsing extremely large cookies.

Ruby is an extensible, interpreted, object-oriented, scripting language. It has features to process text files and to perform system management tasks.

Security Fix(es):

• net-imap: Net::IMAP vulnerable to possible DoS by memory exhaustion (CVE-2025-25186)
• CGI: Denial of Service in CGI::Cookie.parse (CVE-2025-27219)
• uri: userinfo leakage in URI#join, URI#merge and URI#+ (CVE-2025-27221)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Ruby is an extensible, interpreted, object-oriented, scripting language. It has features to process text files and to perform system management tasks.

Security Fix(es):

• rexml: DoS vulnerability in REXML (CVE-2024-39908)
• rexml: rubygem-rexml: DoS when parsing an XML having many specific characters such as whitespace character, >] and ]> (CVE-2024-41123)
• rexml: DoS vulnerability in REXML (CVE-2024-41946)
• rexml: DoS vulnerability in REXML (CVE-2024-43398)
• CGI: ReDoS in CGI::Util#escapeElement (CVE-2025-27220)
• CGI: Denial of Service in CGI::Cookie.parse (CVE-2025-27219)
• uri: userinfo leakage in URI#join, URI#merge and URI#+ (CVE-2025-27221)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Ruby is an extensible, interpreted, object-oriented, scripting language. It has features to process text files and to perform system management tasks.

Security Fix(es):

• rexml: DoS vulnerability in REXML (CVE-2024-39908)
• rexml: rubygem-rexml: DoS when parsing an XML having many specific characters such as whitespace character, >] and ]> (CVE-2024-41123)
• rexml: DoS vulnerability in REXML (CVE-2024-41946)
• rexml: DoS vulnerability in REXML (CVE-2024-43398)
• CGI: ReDoS in CGI::Util#escapeElement (CVE-2025-27220)
• CGI: Denial of Service in CGI::Cookie.parse (CVE-2025-27219)
• uri: userinfo leakage in URI#join, URI#merge and URI#+ (CVE-2025-27221)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Ruby is an extensible, interpreted, object-oriented, scripting language. It has features to process text files and to perform system management tasks.

Security Fix(es):

• net-imap: Net::IMAP vulnerable to possible DoS by memory exhaustion (CVE-2025-25186)
• CGI: Denial of Service in CGI::Cookie.parse (CVE-2025-27219)
• uri: userinfo leakage in URI#join, URI#merge and URI#+ (CVE-2025-27221)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

• CVE-2025-27219: fix a potential Denial of Service (DoS) vulnerability in cookie parsing
• CVE-2025-27220: fix ReDoS vulnerability exists in the escapeElement method
• CVE-2025-27221: fix he URI handling methods (URI.join, URI#merge, URI#+)

Net::IMAP vulnerable to possible DoS by memory exhaustion. (CVE-2025-25186) In the CGI gem before 0.4.2 for Ruby, the CGI::Cookie.parse method in the CGI library contains a potential Denial of Service (DoS) vulnerability. The method does not impose any limit on the length of the raw cookie value it processes. This oversight can lead to excessive resource consumption when parsing extremely large cookies. (CVE-2025-27219) In the CGI gem before 0.4.2 for Ruby, a Regular Expression Denial of Service (ReDoS) vulnerability exists in the Util#escapeElement method. (CVE-2025-27220) In the URI gem before 1.0.3 for Ruby, the URI handling methods (URI.join, URI#merge, URI#+) have an inadvertent leakage of authentication credentials because userinfo is retained even after changing the host. (CVE-2025-27221)

This update for ruby2.5 fixes the following issues:

• CVE-2025-27219: Fixed denial of service in CGI::Cookie.parse (bsc#1237804)
• CVE-2025-27220: Fixed ReDoS in CGI::Util#escapeElement (bsc#1237806)

Other fixes:

• Improved fix for CVE-2024-47220 (bsc#1230930, bsc#1235773)

This update for ruby2.5 fixes the following issues:

• CVE-2024-35221: Fixed remote DoS via YAML manifest (bsc#1225905)
• CVE-2024-47220: Fixed HTTP request smuggling in WEBrick (bsc#1230930)
• CVE-2024-49761: Fixed ReDOS vulnerability by updating REXML to 3.3.9 (bsc#1232440)
• CVE-2025-24294: Fixed denial of service (DoS) caused by an insufficient check on the length of a decompressed domain name within a DNS packet in resolv gem (bsc#1246430)
• CVE-2025-27219: Fixed denial of service in CGI::Cookie.parse (bsc#1237804)
• CVE-2025-27220: Fixed ReDoS in CGI::Util#escapeElement (bsc#1237806)
• CVE-2025-27221: Fixed userinfo leakage in URI#join, URI#merge and URI#+ (bsc#1237805)
• CVE-2025-6442: Fixed ruby WEBrick read_header HTTP request smuggling vulnerability (bsc#1245254)

It was discovered that Ruby incorrectly handled parsing of an XML document that has specific XML characters in an attribute value using REXML gem. An attacker could use this issue to cause Ruby to crash, resulting in a denial of service. This issue only affected in Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 24.10. (CVE-2024-35176, CVE-2024-39908, CVE-2024-41123, CVE-2024-43398)

It was discovered that Ruby incorrectly handled expanding ranges in the net-imap response parser. If a user or automated system were tricked into connecting to a malicious IMAP server, a remote attacker could possibly use this issue to consume memory, leading to a denial of service. This issue only affected Ubuntu 24.04 LTS, and Ubuntu 24.10. (CVE-2025-25186)

It was discovered that the Ruby CGI gem incorrectly handled parsing certain cookies. A remote attacker could possibly use this issue to consume resources, leading to a denial of service. (CVE-2025-27219)

It was discovered that the Ruby CGI gem incorrectly handled parsing certain regular expressions. A remote attacker could possibly use this issue to consume resources, leading to a denial of service. (CVE-2025-27220)

It was discovered that the Ruby URI gem incorrectly handled certain URI handling methods. A remote attacker could possibly use this issue to leak authentication credentials. (CVE-2025-27221)

It was discovered that the Ruby CGI gem incorrectly handled parsing certain cookies. A remote attacker could possibly use this issue to consume resources, leading to a denial of service. (CVE-2025-27219)

It was discovered that the Ruby CGI gem incorrectly handled parsing certain regular expressions. A remote attacker could possibly use this issue to consume resources, leading to a denial of service. (CVE-2025-27220)

It was discovered that the Ruby URI gem incorrectly handled certain URI handling methods. A remote attacker could possibly use this issue to leak authentication credentials. (CVE-2025-27221)

It was discovered that the Ruby REXML gem incorrectly handled parsing XML documents containing many digits in a hex numeric character reference. A remote attacker could use this issue to consume resources, leading to a denial of service. (CVE-2024-49761)