CVE-2021-29481
Client side sessions should not allow unencrypted storage
CVE-2021-29481 is a medium vulnerability (CVSS 6.5) in Ratpack, published June 29, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.46%, the 39th percentile. Fixed in io.ratpack:ratpack-session 1.9.0.
Ratpack is a toolkit for creating web applications. In versions prior to 1.9.0, the default configuration of client side sessions results in unencrypted, but signed, data being set as cookie values. This means that if something sensitive goes into the session, it could be read by something with access to the cookies. For this to be a vulnerability, some kind of sensitive data would need to be stored in the session and the session cookie would have to leak. For example, the cookies are not configured with httpOnly and an adjacent XSS vulnerability within the site allowed capture of the cookies. As of version 1.9.0, a securely randomly generated signing key is used. As a workaround, one may supply an encryption key, as per the documentation recommendation.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Client side sessions should not allow unencrypted storage
Ratpack is a toolkit for creating web applications. In versions prior to 1.9.0, the default configuration of client side sessions results in unencrypted, but signed, data being set as cookie values. This means that if something sensitive goes into the session, it could be read by something with access to the cookies. For this to be a vulnerability, some kind of sensitive data would need to be stored in the session and the session cookie would have to leak. For example, the cookies are not configured with httpOnly and an adjacent XSS vulnerability within the site allowed capture of the cookies. As of version 1.9.0, a securely randomly generated signing key is used. As a workaround, one may supply an encryption key, as per the documentation recommendation.
- Record
CVE-2021-29481- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N - Weakness
- CWE-312
- Updated
- 2026-11-02
EUVDEUVD-2021-1484
Ratpack is a toolkit for creating web applications. In versions prior to 1.9.0, the default configuration of client side sessions results in unencrypted, but signed, data being set as cookie values. This means that if something sensitive goes into the session, it could be read by something with access to the cookies. For this to be a vulnerability, some kind of sensitive data would need to be stored in the session and the session cookie would have to leak. For example, the cookies are not configured with httpOnly and an adjacent XSS vulnerability within the site allowed capture of the cookies. As of version 1.9.0, a securely randomly generated signing key is used. As a workaround, one may supply an encryption key, as per the documentation recommendation.
- Record
EUVD-2021-1484- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-phj8-4cq3-794g
Unencrypted storage of client side sessions
Impact
The default configuration of client side sessions results in unencrypted, but signed, data being set as cookie values. This means that if something sensitive goes into the session, it could be read by something with access to the cookies.
Note: the documentation does point this out and encourage users to add an encryption key, but it is not mandatory.
For this to be a vulnerability, some kind of sensitive data would need to be stored in the session and the session cookie would have to leak. For example, the cookies are not configured with httpOnly and an adjacent XSS vulnerability within the site allowed capture of the cookies.
The proposed change is to change the default behaviour to use a randomly generated encryption key. This would mean that sessions do not survive app restarts, but this is already the behaviour given the random signing key.
Patches
As of version 1.9.0, a securely randomly generated signing key is used.
Workarounds
Supply an encryption key, as per the documentation recommendation.
References
- Record
GHSA-phj8-4cq3-794g- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N - Weakness
- CWE-312
- Updated
- 2026-11-02
NVD
Ratpack is a toolkit for creating web applications. In versions prior to 1.9.0, the default configuration of client side sessions results in unencrypted, but signed, data being set as cookie values. This means that if something sensitive goes into the session, it could be read by something with access to the cookies. For this to be a vulnerability, some kind of sensitive data would need to be stored in the session and the session cookie would have to leak. For example, the cookies are not configured with httpOnly and an adjacent XSS vulnerability within the site allowed capture of the cookies. As of version 1.9.0, a securely randomly generated signing key is used. As a workaround, one may supply an encryption key, as per the documentation recommendation.
- Record
CVE-2021-29481- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:P/I:N/A:N - Weakness
- CWE-312
- Updated
- 2026-11-02
OSV
Ratpack is a toolkit for creating web applications. In versions prior to 1.9.0, the default configuration of client side sessions results in unencrypted, but signed, data being set as cookie values. This means that if something sensitive goes into the session, it could be read by something with access to the cookies. For this to be a vulnerability, some kind of sensitive data would need to be stored in the session and the session cookie would have to leak. For example, the cookies are not configured with httpOnly and an adjacent XSS vulnerability within the site allowed capture of the cookies. As of version 1.9.0, a securely randomly generated signing key is used. As a workaround, one may supply an encryption key, as per the documentation recommendation.
- Record
CVE-2021-29481- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-02
OSVGHSA-phj8-4cq3-794g
Unencrypted storage of client side sessions
Impact
The default configuration of client side sessions results in unencrypted, but signed, data being set as cookie values. This means that if something sensitive goes into the session, it could be read by something with access to the cookies.
Note: the documentation does point this out and encourage users to add an encryption key, but it is not mandatory.
For this to be a vulnerability, some kind of sensitive data would need to be stored in the session and the session cookie would have to leak. For example, the cookies are not configured with httpOnly and an adjacent XSS vulnerability within the site allowed capture of the cookies.
The proposed change is to change the default behaviour to use a randomly generated encryption key. This would mean that sessions do not survive app restarts, but this is already the behaviour given the random signing key.
Patches
As of version 1.9.0, a securely randomly generated signing key is used.
Workarounds
Supply an encryption key, as per the documentation recommendation.
References
- Record
GHSA-phj8-4cq3-794g- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N - Weakness
- CWE-312
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
io.ratpack:ratpack-sessionMaven |
before 1.9.0 | 1.9.0 |
io.ratpack:ratpack-sessionMaven |
before 1.9.0, plus listed versions 0.9.00.9.10.9.100.9.110.9.12 Show 45 moreShow less0.9.130.9.140.9.150.9.160.9.170.9.180.9.190.9.20.9.30.9.40.9.50.9.60.9.70.9.80.9.91.0.01.0.0-rc-11.0.0-rc-21.0.0-rc-31.1.01.1.11.2.01.2.0-RC-11.2.0-rc-21.3.01.3.0-rc-11.3.0-rc-21.3.11.3.21.3.31.4.01.4.0-rc-11.4.0-rc-21.4.0-rc-31.4.11.4.21.4.31.4.41.4.51.4.61.5.01.5.11.5.21.5.31.5.4 |
1.9.0 |
History
| When | Changed | Sources |
|---|---|---|
| 2026-11-03 | aliases | EUVD |
| 2026-11-02 | created | CVE List, GitHub Advisories, NVD, OSV |
References
Left out here: 18 versions. The JSON record has them.