# CVE-2021-29481: Client side sessions should not allow unencrypted storage

> Attackers can read sensitive session data from unencrypted cookies if they leak, affecting developers using Ratpack web toolkit.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 29 Jun 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-phj8-4cq3-794g

## What is CVE-2021-29481?

CVE-2021-29481 is a medium-severity vulnerability in ratpack, published on 29 Jun 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

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.

Weakness: CWE-312 (Cleartext Storage of Sensitive Information)

## Which versions are affected by CVE-2021-29481?

2 open source packages ship an affected version, including io.ratpack:ratpack-session. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `io.ratpack:ratpack-session` | Maven | All versions | 1.9.0 |
| `io.ratpack:ratpack-session` | Maven | All versions | 1.9.0 |

Products: Ratpack Project Ratpack.

## How do I fix CVE-2021-29481?

Upgrade io.ratpack:ratpack-session to 1.9.0 or later.

## Is CVE-2021-29481 being exploited?

There is no known exploitation of CVE-2021-29481 in the wild and no public exploit code.

## Other vulnerabilities in ratpack

- [CVE-2021-29485](https://insights.sbomify.com/CVE-2021-29485/): Remote Code Execution Vulnerability in Session Storage (critical 9.9)
- [CVE-2019-17513](https://insights.sbomify.com/CVE-2019-17513/): io.ratpack:ratpack-core vulnerable to Improper Neutralization of Special Elements in Output ('Injection') (high 7.5)
- [CVE-2021-29479](https://insights.sbomify.com/CVE-2021-29479/): Cached redirect poisoning via X-Forwarded-Host header (high 7.0)
- [CVE-2021-29480](https://insights.sbomify.com/CVE-2021-29480/): Default client side session signing key is highly predictable (medium 4.4)
- [CVE-2019-11808](https://insights.sbomify.com/CVE-2019-11808/): Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) in Ratpack (low 3.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-29481 and fix it if it is affected.

What it is: CVE-2021-29481 is a medium-severity vulnerability in ratpack, published on 29 Jun 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-29481 in the wild and no public exploit code.

Affected packages and fixed versions:
- io.ratpack:ratpack-session (Maven): affected all versions; fixed in 1.9.0
- io.ratpack:ratpack-session (Maven): affected all versions; fixed in 1.9.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-29481/ (Markdown: https://insights.sbomify.com/CVE-2021-29481/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-29481
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-29481
- OSV: https://osv.dev/vulnerability/CVE-2021-29481

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-29481/
Summaries are generated and may contain mistakes; the official description above is the record.