CVE-2021-29480

Session-data tampering via predictable signing key

Published Jun 29, 2021 · Updated Aug 3, 2024

Predictable signing keys in Ratpack before 1.9.0 allow attackers to tamper with client-side session data through crafted cookies. ClientSideSessionConfig derives the default secretToken from System.currentTimeMillis() divided into 10-second intervals, making the HMAC signing secret guessable. Exploitation requires the client-side session module, its default signing key, disabled encryption, knowledge of application startup time, and the ability to write cookies; the resulting impact is limited to session-data integrity.

CVSS severity4.4
Medium
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Predictable signing keys in Ratpack before 1.9.0 allow attackers to tamper with client-side session data through crafted cookies. ClientSideSessionConfig derives the default secretToken from System.currentTimeMillis() divided into 10-second intervals, making the HMAC signing secret guessable. Exploitation requires the client-side session module, its default signing key, disabled encryption, knowledge of application startup time, and the ability to write cookies; the resulting impact is limited to session-data integrity.

The record

CVE
CVE-2021-29480
Published
Jun 29, 2021
Updated
Aug 3, 2024
Vendor
Ratpack
Product
Ratpack
Classifications
CWE-340, CWE-330, T1606.001
Attack vector
Unavailable
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 29, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.9.0

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesauthenticated

What is affected?

Ratpack · Ratpackversion=< 1.9.0

Published CVSS scores

3.1NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N
4.4GitHub, Inc.CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
3.5NIST National Vulnerability DatabaseAV:N/AC:M/Au:S/C:N/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
VectorUnavailable
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-340Generation of Predictable Numbers or Identifiers
CWE-330Use of Insufficiently Random Values
T1606.001Forge Web Credentials: Web Cookies

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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