CVE-2021-29479 | Cached redirect poisoning via X-Forwarded-Host header

Exp

Ratpack is a toolkit for creating web applications. In versions prior to 1.9.0, a user supplied `X-Forwarded-Host` header can be used to perform cache poisoning of a cache fronting a Ratpack server if the cache key does not include the `X-Forwarded-Host` header as a cache key. Users are only vulnerable if they do not configure a custom `PublicAddress` instance. For versions prior to 1.9.0, by default, Ratpack utilizes an inferring version of `PublicAddress` which is vulnerable. This can be used to perform redirect cache poisoning where an attacker can force a cached redirect to redirect to their site instead of the intended redirect location. The vulnerability was patched in Ratpack 1.9.0. As a workaround, ensure that `ServerConfigBuilder::publicAddress` correctly configures the server in production.

Published: 2021-06-29 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-29479 is rated High Exploit Risk (62.4/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.86%). 1 public exploit reference(s) are indexed (Exploit-DB). 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-2021-29479

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

Exploit prediction scoring system (EPSS) score for CVE-2021-29479

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 0.22% 0.86% +0.63%
2 2025-03-17 0.07% 0.22% +0.16%
3 2023-03-07 — 0.07% —

Full EPSS history (7 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-29479

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.0 3.1 HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/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:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
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:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 2.2 4.7 [email protected]
6.1 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
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:N)
Service keeps running; no real outage angle.
 2.8 2.7 [email protected]
4.0 2.0 MEDIUM
AV:N/AC:H/Au:N/C:P/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:H)
Exploitation requires uncommon or highly specific conditions.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 4.9 4.9 [email protected]

Weakness enumeration for CVE-2021-29479

GitHub Security Advisory for CVE-2021-29479

GHSA-w6rq-6h34-vh7q · Severity: high · Ecosystem: maven — Cached redirect poisoning via X-Forwarded-Host header

Affected software / configurations for CVE-2021-29479

Vendor Product Version Raw CPE
ratpack_project ratpack < 1.9.0 cpe:2.3:a:ratpack_project:ratpack:*:*:*:*:*:*:*:*

References for CVE-2021-29479

cvelogic Threat Intelligence