CVE-2021-28966

Exp

In Ruby through 3.0 on Windows, a remote attacker can submit a crafted path when a Web application handles a parameter with TmpDir.

Published: 2021-07-30 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-28966 is rated High Exploit Risk (84.6/100): CVSS High severity, with high exploitation likelihood (EPSS 58.04%, 99th percentile). 1 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +57.79% 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-2021-28966

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

Exploit prediction scoring system (EPSS) score for CVE-2021-28966

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 0.25% 58.04% +57.79%
2 2026-06-01 0.35% 0.25% -0.10%
3 2025-11-21 — 0.35% —

Full EPSS history (19 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-28966

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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:N)
No account or special rights needed—anonymous or random user is enough.
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:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:P/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:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-28966

GitHub Security Advisory for CVE-2021-28966

GHSA-46f2-3v63-3xrp · Severity: high · Ecosystem: rubygems — Tempfile on Windows path traversal vulnerability

OS Trackers for CVE-2021-28966

vendor priority summary link
alpine high CVE-2021-28966: 1 source package rows (ruby); 10 state rows across 10 repos (3.10-main, 3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 10, open 0. https://security.alpinelinux.org/vuln/CVE-2021-28966
debian unimportant CVE-2021-28966 unimportant priority: Debian including 1 source packages (ruby2.7), 1 status rows across 1 suites (bullseye): resolved 1. https://security-tracker.debian.org/tracker/CVE-2021-28966
ubuntu low CVE-2021-28966 low priority: Ubuntu including 1 source packages (ruby2.7), 7 status rows across 7 suites (bionic, focal, hirsute, impish, trusty, upstream, xenial): ignored 3, DNE 2, not-affected 2. https://ubuntu.com/security/CVE-2021-28966

Affected software / configurations for CVE-2021-28966

Vendor Product Version Raw CPE
ruby-lang ruby < 2.7.3 cpe:2.3:a:ruby-lang:ruby:*:*:*:*:*:*:*:*
ruby-lang ruby >= 3.0.0, < 3.0.1 cpe:2.3:a:ruby-lang:ruby:*:*:*:*:*:*:*:*

References for CVE-2021-28966

URL Tags
https://hackerone.com/reports/1131465 Exploit Issue Tracking Patch Third Party Advisory
https://security.netapp.com/advisory/ntap-20210902-0004/ Third Party Advisory
cvelogic Threat Intelligence