CVE-2019-10842
Bootstrap-sass contains code execution backdoor
CVE-2019-10842 is a critical vulnerability (CVSS 9.8) in Getbootstrap Bootstrap-sass, published April 4, 2019. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 4.92%, the 92nd percentile. Fixed in bootstrap-sass 3.2.0.4.
Arbitrary code execution (via backdoor code) was discovered in bootstrap-sass 3.2.0.3, when downloaded from rubygems.org. An unauthenticated attacker can craft the ___cfduid cookie value with base64 arbitrary code to be executed via eval(), which can be leveraged to execute arbitrary code on the target system. Note that there are three underscore characters in the cookie name. This is unrelated to the __cfduid cookie that is legitimately used by Cloudflare.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
9.8
Arbitrary code execution (via backdoor code) was discovered in bootstrap-sass 3.2.0.3, when downloaded from rubygems.org. An unauthenticated attacker can craft the ___cfduid cookie value with base64 arbitrary code to be executed via eval(), which can be leveraged to execute arbitrary code on the target system. Note that there are three underscore characters in the cookie name. This is unrelated to the __cfduid cookie that is legitimately used by Cloudflare.
- Record
CVE-2019-10842- CVSS 3.0
- 9.8 Critical
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 2.0
- 10.0 High
AV:N/AC:L/Au:N/C:C/I:C/A:C - Weakness
- CWE-94
- Updated
- 2026-11-02
CVE List No score
Arbitrary code execution (via backdoor code) was discovered in bootstrap-sass 3.2.0.3, when downloaded from rubygems.org. An unauthenticated attacker can craft the ___cfduid cookie value with base64 arbitrary code to be executed via eval(), which can be leveraged to execute arbitrary code on the target system. Note that there are three underscore characters in the cookie name. This is unrelated to the __cfduid cookie that is legitimately used by Cloudflare.
- Record
CVE-2019-10842- Updated
- 2026-11-02
EUVDEUVD-2019-0438 No score
Arbitrary code execution (via backdoor code) was discovered in bootstrap-sass 3.2.0.3, when downloaded from rubygems.org. An unauthenticated attacker can craft the ___cfduid cookie value with base64 arbitrary code to be executed via eval(), which can be leveraged to execute arbitrary code on the target system. Note that there are three underscore characters in the cookie name. This is unrelated to the __cfduid cookie that is legitimately used by Cloudflare.
- Record
EUVD-2019-0438- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-vqqv-v9m2-48p2
9.8
Bootstrap-sass contains code execution backdoor
Arbitrary code execution (via backdoor code) was discovered in bootstrap-sass 3.2.0.3, when downloaded from rubygems.org. An unauthenticated attacker can craft the ___cfduid cookie value with base64 arbitrary code to be executed via eval(), which can be leveraged to execute arbitrary code on the target system. Note that there are three underscore characters in the cookie name. This is unrelated to the __cfduid cookie that is legitimately used by Cloudflare.
- Record
GHSA-vqqv-v9m2-48p2- CVSS 3.0
- 9.8 Critical
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-94
- Updated
- 2026-11-02
OSVGHSA-vqqv-v9m2-48p2
9.8
Bootstrap-sass contains code execution backdoor
Arbitrary code execution (via backdoor code) was discovered in bootstrap-sass 3.2.0.3, when downloaded from rubygems.org. An unauthenticated attacker can craft the ___cfduid cookie value with base64 arbitrary code to be executed via eval(), which can be leveraged to execute arbitrary code on the target system. Note that there are three underscore characters in the cookie name. This is unrelated to the __cfduid cookie that is legitimately used by Cloudflare.
- Record
GHSA-vqqv-v9m2-48p2- CVSS 3.0
- 9.8 Critical
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-94
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
bootstrap-sassRubyGems |
3.2.0.3 to 3.2.0.3 | 3.2.0.4 |
bootstrap-sassRubyGems |
3.2.0.3 up to 3.2.0.4 | 3.2.0.4 |
History
| When | Changed | Sources |
|---|---|---|
| 2026-11-03 | aliases | EUVD |
| 2026-11-02 | created | CVE List, GitHub Advisories, NVD, OSV |
References
github.com/twbs/bootstrap-sass/issues/1195
snyk.io/blog/malicious-remote-code-execution-backdoor-discovered-in-the-popular-bootstrap-sass-ruby-gem
snyk.io/vuln/SNYK-RUBY-BOOTSTRAPSASS-174093
dgb.github.io/2019/04/05/bootstrap-sass-backdoor.html
nvd.nist.gov/vuln/detail/CVE-2019-10842
github.com/rubysec/ruby-advisory-db/blob/master/gems/bootstrap-sass/CVE-2019-10842.yml
github.com/advisories/GHSA-vqqv-v9m2-48p2
github.com/twbs/bootstrap-sass