CVE-2019-10842: Arbitrary code execution (via backdoor code) was discovered in bootstrap-sass 3.2.0.3, when downloaded from ru

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CRITICAL 9.8REMOTEDOWNGRADE

CVE-2019-10842 is a critical-severity flaw (CVSS 9.8) affecting bootstrap-sass. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

Critical severity
EPSS top 8%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	4.9% (top 8%)
CISA exploited list	No
Weakness	CWE-94
Published	2019-04-04
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: getbootstrap

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2019-04-04 04:29 UTCPublished CVE record published
2026-06-17 02:11 UTCUpdated Record last modified

getbootstrap bootstrap-sass DOWNGRADE

Affected: 3.2.0.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.2.0.3

1. Check installed version

apt-cache policy bootstrap-sass || rpm -q bootstrap-sass || bootstrap-sass --version

2. No fixed release: DOWNGRADE to a release before 3.2.0.3 (Debian / Ubuntu)

apt-cache madison bootstrap-sass sudo apt install bootstrap-sass=<VERSION_BEFORE_3.2.0.3> sudo apt-mark hold bootstrap-sass

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list bootstrap-sass sudo dnf downgrade bootstrap-sass-<VERSION_BEFORE_3.2.0.3> sudo dnf versionlock add bootstrap-sass

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2019-10842?

bootstrap-sass: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2019-10842 being exploited?

CVE-2019-10842 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2019-10842 affect?

CVE-2019-10842 affects bootstrap-sass. Severity is critical (CVSS 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(),

How urgent is CVE-2019-10842?

Priority 67/100. Critical severity; EPSS top 8%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

Bootstrap vulnerabilities

References

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