CVE-2021-41263

Secure/signed cookies share secrets between sites in rails_multisite

HIGH
8.8
CVSS Score
Published: November 15, 2021 at 08:10 PM UTC
Updated: June 17, 2026 at 04:08 AM UTC
1 product affected across 1 vendorRails Multisite

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Severity
HIGH8.8
Exploit prediction
EPSS 0.6%

Description

rails_multisite provides multi-db support for Rails applications. In affected versions this vulnerability impacts any Rails applications using `rails_multisite` alongside Rails' signed/encrypted cookies. Depending on how the application makes use of these cookies, it may be possible for an attacker to re-use cookies on different 'sites' within a multi-site Rails application. The issue has been patched in v4 of the `rails_multisite` gem. Note that this upgrade will invalidate all previous signed/encrypted cookies. The impact of this invalidation will vary based on the application architecture.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 4.0.0
Affected range stops below 4.0.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-200CWE-565CWE-327

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