CVE-2021-29485: Ratpack is a toolkit for creating web applications

Q: How do I fix CVE-2021-29485?

ratpack: upgrade to 1.9.0. Exact commands for each OS are on this page.

Q: Is CVE-2021-29485 being exploited?

CVE-2021-29485 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-29485 affect?

CVE-2021-29485 affects ratpack. Severity is critical (CVSS 9.9). Ratpack is a toolkit for creating web applications. In versions prior to 1.9.0, a malicious attacker can achieve Remote Code Execution (RCE) via a maliciously crafted Java deserialization gadget chain leveraged against the Ratpack session s

Q: How urgent is CVE-2021-29485?

Priority 55/100. Critical severity

This month

CRITICAL 9.9UPGRADE

CVE-2021-29485 is a critical-severity flaw (CVSS 9.9) affecting ratpack. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Ratpack is a toolkit for creating web applications. In versions prior to 1.9.0, a malicious attacker can achieve Remote Code Execution (RCE) via a maliciously crafted Java deserialization gadget chain leveraged against the Ratpack session store. If one's application does not use Ratpack's session mechanism, it is not vulnerable. Ratpack 1.9.0 introduces a strict allow-list mechanism that mitigates this vulnerability when used. Two possible workar

Why this priority

Critical severity

A fixed release or distro patch exists.

Risk facts

CVSS score	9.9 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	2.0% (top 19%)
CISA exploited list	No
Weakness	CWE-502
Published	2021-06-29
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: ratpack project

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

Am I affected?

Timeline

2021-06-29 19:15 UTCPublished CVE record published
2026-06-17 03:47 UTCUpdated Record last modified

ratpack project ratpack UPGRADE

Affected: < 1.9.0

Fixed in: 1.9.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy ratpack || rpm -q ratpack || ratpack --version

2. UPGRADE to 1.9.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade ratpack

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade ratpack

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2021-29485?

ratpack: upgrade to 1.9.0. Exact commands for each OS are on this page.

Is CVE-2021-29485 being exploited?

CVE-2021-29485 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-2021-29485 affect?

CVE-2021-29485 affects ratpack. Severity is critical (CVSS 9.9). Ratpack is a toolkit for creating web applications. In versions prior to 1.9.0, a malicious attacker can achieve Remote Code Execution (RCE) via a maliciously crafted Java deserialization gadget chain leveraged against the Ratpack session s

How urgent is CVE-2021-29485?

Priority 55/100. Critical severity

Software pages

Java vulnerabilities

Related CVEs

CVE-2021-29481 MEDIUM 6.5 UPGRADE Ratpack is a toolkit for creating web applications
CVE-2021-29480 MEDIUM 4.4 UPGRADE Ratpack is a toolkit for creating web applications
CVE-2021-29479 HIGH 7.0 UPGRADE Ratpack is a toolkit for creating web applications
CVE-2019-10770 MEDIUM 6.1 UPGRADE All versions of io.ratpack:ratpack-core from 0.9.10 inclusive and before 1.7.6 are vulnerable to Cross-site Sc

References

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