CVE-2021-29480: Ratpack is a toolkit for creating web applications

Q: How do I fix CVE-2021-29480?

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

Q: Is CVE-2021-29480 being exploited?

CVE-2021-29480 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-2021-29480 affect?

CVE-2021-29480 affects ratpack. Severity is medium (CVSS 4.4). Ratpack is a toolkit for creating web applications. In versions prior to 1.9.0, the client side session module uses the application startup time as the signing key by default. This means that if an attacker can determine this time, and if e

Q: How urgent is CVE-2021-29480?

Priority 20/100. No elevated risk signals yet.

Routine

MEDIUM 4.4UPGRADE

CVE-2021-29480 is a medium-severity flaw (CVSS 4.4) 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, the client side session module uses the application startup time as the signing key by default. This means that if an attacker can determine this time, and if encryption is not also used (which is recommended, but is not on by default), the session data could be tampered with by someone with the ability to write cookies. The default configuration is unsuitable for pro

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	4.4 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.3% (top 82%)
CISA exploited list	No
Weakness	CWE-340, CWE-330
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-2021-29480?

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

Is CVE-2021-29480 being exploited?

CVE-2021-29480 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-2021-29480 affect?

CVE-2021-29480 affects ratpack. Severity is medium (CVSS 4.4). Ratpack is a toolkit for creating web applications. In versions prior to 1.9.0, the client side session module uses the application startup time as the signing key by default. This means that if an attacker can determine this time, and if e

How urgent is CVE-2021-29480?

Priority 20/100. No elevated risk signals yet.

Related CVEs

CVE-2021-29485 CRITICAL 9.9 UPGRADE Ratpack is a toolkit for creating web applications
CVE-2021-29481 MEDIUM 6.5 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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