CVE-2021-21305 | Code Injection vulnerability in CarrierWave

Exp

CarrierWave is an open-source RubyGem which provides a simple and flexible way to upload files from Ruby applications. In CarrierWave before versions 1.3.2 and 2.1.1, there is a code injection vulnerability. The "#manipulate!" method inappropriately evals the content of mutation option(:read/:write), allowing attackers to craft a string that can be executed as a Ruby code. If an application developer supplies untrusted inputs to the option, it will lead to remote code execution(RCE). This is fixed in versions 1.3.2 and 2.1.1.

Published: 2021-02-08 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-21305 is rated High Exploit Risk (83.1/100): CVSS High severity, with high exploitation likelihood (EPSS 12.68%, 96th percentile). 1 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +9.86% over the last day, indicating growing attacker interest. Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-21305

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-21305

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 2.82% 12.68% +9.86%
2 2025-11-21 3.63% 2.82% -0.81%
3 2025-11-18 — 3.63% —

Full EPSS history (19 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-21305

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.4 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.1 3.7 [email protected]
8.8 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 5.9 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2021-21305

GitHub Security Advisory for CVE-2021-21305

GHSA-cf3w-g86h-35x4 · Severity: high · Ecosystem: rubygems — Code Injection vulnerability in CarrierWave::RMagick

OS Trackers for CVE-2021-21305

vendor priority summary link
debian not yet assigned CVE-2021-21305 not yet assigned priority: Debian including 1 source packages (ruby-carrierwave), 1 status rows across 1 suites (bookworm): resolved 1. https://security-tracker.debian.org/tracker/CVE-2021-21305
ubuntu medium CVE-2021-21305 medium priority: Ubuntu including 1 source packages (ruby-carrierwave), 16 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): ignored 6, not-affected 4, released 3, DNE 2, needed 1. https://ubuntu.com/security/CVE-2021-21305

Affected software / configurations for CVE-2021-21305

Vendor Product Version Raw CPE
carrierwave_project carrierwave < 1.3.2 cpe:2.3:a:carrierwave_project:carrierwave:*:*:*:*:*:ruby:*:*
carrierwave_project carrierwave >= 2.0.1, < 2.1.1 cpe:2.3:a:carrierwave_project:carrierwave:*:*:*:*:*:ruby:*:*

References for CVE-2021-21305

cvelogic Threat Intelligence