CVE-2021-29485

CVE-2021-29485 is a critical-severity vulnerability in Ratpack Project Ratpack with a CVSS 3.x base score of 9.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-502.

Key facts

Description

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 workarounds exist. The simplest mitigation for users of earlier versions is to reduce the likelihood of attackers being able to write to the session data store. Alternatively or additionally, the allow-list mechanism could be manually back ported by providing an alternative implementation of `SessionSerializer` that uses an allow-list.

Frequently asked questions

What is CVE-2021-29485?
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 workarounds exist. The simplest mitigation for users of earlier versions is to reduce the likelihood of attackers being able to write to the session data store. Alternatively or additionally, the allow-list mechanism could be manually back ported by providing an alternative implementation of `SessionSerializer` that uses an allow-list.
How severe is CVE-2021-29485?
CVE-2021-29485 has a CVSS 3.x base score of 9.9, rated critical severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-29485 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-29485?
CVE-2021-29485 affects Ratpack Project Ratpack. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-29485?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-29485 published?
CVE-2021-29485 was published on 2021-06-29 and last updated on 2026-06-17.

References

Affected products (1)

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