CVE-2021-29480 Default client side session signing key is highly predictable
Attackers can tamper with session data if they predict the application startup time, as the default signing key is weak and predictable.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-29480?
CVE-2021-29480 is a medium-severity vulnerability in ratpack, published on 29 Jun 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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 production use as an application restart renders all sessions invalid and is not multi-host compatible, but its use is not actively prevented. As of Ratpack 1.9.0, the default value is a securely randomly generated value, generated at application startup time. As a workaround, supply an alternative signing key, as per the documentation's recommendation.
Which versions are affected by CVE-2021-29480?
2 open source packages ship an affected version, including io.ratpack:ratpack-session. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
io.ratpack:ratpack-session Maven | All versions | 1.9.0 |
io.ratpack:ratpack-session Maven | All versions | 1.9.0 |
Products include Ratpack Project Ratpack.
How do I fix CVE-2021-29480?
Upgrade io.ratpack:ratpack-session to 1.9.0 or later.
Is CVE-2021-29480 being exploited?
There is no known exploitation of CVE-2021-29480 in the wild and no public exploit code.
Other vulnerabilities in ratpack
- CVE-2021-29485 Remote Code Execution Vulnerability in Session Storage
- CVE-2019-17513 io.ratpack:ratpack-core vulnerable to Improper Neutralization of Special Elements in Output ('Injection')
- CVE-2021-29479 Cached redirect poisoning via X-Forwarded-Host header
- CVE-2021-29481 Client side sessions should not allow unencrypted storage
- CVE-2019-11808 Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) in Ratpack
Sources
Also known as GHSA-2cc5-23r7-vc4v.