CVE-2021-21288 | Server-side request forgery in CarrierWave

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 the download feature has an SSRF vulnerability, allowing attacks to provide DNS entries or IP addresses that are intended for internal use and gather information about the Intranet infrastructure of the platform. This is fixed in versions 1.3.2 and 2.1.1.

Published: 2021-02-08 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-21288 is rated Low Risk (30.8/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.20%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

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

Exploit prediction scoring system (EPSS) score for CVE-2021-21288

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 2025-03-30 0.26% 0.20% -0.06%
2 2025-03-29 0.20% 0.26% +0.06%
3 2025-03-17 — 0.20% —

Full EPSS history (8 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-21288

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N 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:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 1.4 [email protected]
4.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N 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:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 1.4 [email protected]
4.0 2.0 MEDIUM
AV:N/AC:L/Au:S/C:P/I:N/A:N 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:S)
A single authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 8.0 2.9 [email protected]

Weakness enumeration for CVE-2021-21288

GitHub Security Advisory for CVE-2021-21288

GHSA-fwcm-636p-68r5 · Severity: medium · Ecosystem: rubygems — Server-side request forgery in CarrierWave

OS Trackers for CVE-2021-21288

vendor priority summary link
debian not yet assigned CVE-2021-21288 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-2021-21288
ubuntu medium CVE-2021-21288 medium priority: Ubuntu including 1 source packages (ruby-carrierwave), 15 status rows across 15 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, trusty, upstream, xenial): not-affected 7, ignored 6, DNE 1, released 1. https://ubuntu.com/security/CVE-2021-21288

Affected software / configurations for CVE-2021-21288

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-2021-21288

cvelogic Threat Intelligence