CVE-2021-39197: Better errors Older Releases Of Better_errors Open Vulnerability
MODERATECVE-2021-39197 is a MODERATE (CVSS 6.3) older releases of better_errors open vulnerability (CWE-352: Cross-Site Request Forgery (CSRF)) affecting Better errors libraries in the RubyGems ecosystem. The issue involves older releases of better_errors open to cross-site request forgery attack. Remediation is available by upgrading affected packages to version 2.8.0.
CVE-2021-39197 at a Glance
Security Impact
CVSS: 6.3
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N).
How to Fix CVE-2021-39197
To remediate this vulnerability, upgrade all affected Better errors dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
Upgrade better_errors to 2.8.0Run the following command in your project directory to verify that all resolved dependencies use the patched release:
inspect dependencies for better_errorsHow to Check if You Are Affected
To determine whether your application is affected by CVE-2021-39197, inspect your project dependencies for Better errors:
inspect dependencies for better_errorsAnalyze the terminal output to locate any version of Better errors in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.8.0), your application is affected.
Note: Verify declared build manifests and deployed runtime container environments.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-352: Cross-Site Request Forgery (CSRF), where the web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor. In Better errors, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2021-39197 Affected Better errors Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
better_errors
|
RubyGems |
< 2.8.0
|
2.8.0
|
References
Frequently Asked Questions
What is CVE-2021-39197?
Which Better errors versions are affected?
What version fixes CVE-2021-39197?
Is better_errors affected?
What is the CVSS score of CVE-2021-39197?
What CWE is associated with CVE-2021-39197?
How can I check RubyGems dependencies for CVE-2021-39197?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-w3j4-76qw-wwjm",
"modified" : "2021-09-08T14:47:05Z",
"published" : "2021-09-07T23:08:24Z",
"aliases" : [ "CVE-2021-39197" ],
"summary" : "Older releases of better_errors open to Cross-Site Request Forgery attack",
"details" : "### Impact\nbetter_errors prior to 2.8.0 did not implement CSRF protection for its internal requests. It also did not enforce the correct \"Content-Type\" header for these requests, which allowed a cross-origin \"simple request\" to be made without CORS protection. These together left an application with better_errors enabled open to cross-origin attacks.\n\n_As a developer tool, better_errors documentation strongly recommends addition only to the `development` bundle group, so this vulnerability should only affect development environments. Please ensure that your project limits better_errors to the `development` group (or the non-Rails equivalent)._\n\n### Patches\nStarting with release 2.8.x, CSRF protection is enforced. It is recommended that you upgrade to the latest release, or minimally to \"~> 2.8.3\".\n\n### Workarounds\nThere are no known workarounds to mitigate the risk of using older releases of better_errors.\n\n### References\n- Chris Moberly provided [an example attack that uses a now-patched vulnerability of webpack-dev-server in conjunction with Better Errors](https://about.gitlab.com/blog/2021/09/07/why-are-developers-vulnerable-to-driveby-attacks/)\n\n### For more information\nIf you have any questions or comments about this advisory, please\n- Add to the [discussion in better_errors](https://github.com/BetterErrors/better_errors/discussions/507)\n- Open an issue in [better_errors](https://github.com/BetterErrors/better_errors)\n",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "RubyGems",
"name" : "better_errors"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "2.8.0"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/BetterErrors/better_errors/security/advisories/GHSA-w3j4-76qw-wwjm"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-39197"
}, {
"type" : "WEB",
"url" : "https://github.com/BetterErrors/better_errors/pull/474"
}, {
"type" : "WEB",
"url" : "https://github.com/BetterErrors/better_errors/commit/8e8e796bfbde4aa088741823c8a3fc6df2089bb0"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/BetterErrors/better_errors"
}, {
"type" : "WEB",
"url" : "https://github.com/BetterErrors/better_errors/discussions/507"
}, {
"type" : "WEB",
"url" : "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/better_errors/CVE-2021-39197.yml"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-352" ],
"severity" : "MODERATE",
"github_reviewed" : true,
"github_reviewed_at" : "2021-09-07T17:58:52Z",
"nvd_published_at" : "2021-09-07T18:15:00Z"
}
}