CVE-2021-41263Secure/signed cookies share secrets between sites in rails_multisite
- 8.3HighCVSS base score
- 0.63%Exploitation in 30 daysEPSS · top 49% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By GitHub_M
- 2 months later
· 2 months later
Published
- 3 years later
· 3 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | High8.3 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H |
| NVDNVD · Modified | 3.1 | High8.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.63% · top 49% of all CVEs (12 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.3.
Affected products
- affected < 4.0.0
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- RubyGemsrails_multisiteGHSA-844m-cpr9-jcmh (opens in a new tab)
References
References2
- https://github.com/discourse/rails_multisite/security/advisories/GHSA-844m-cpr9-jcmh (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://github.com/discourse/rails_multisite/commit/c6785cdb5c9277dd2c5ac8d55180dd1ece440ed0 (opens in a new tab)x_refsource_MISCx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2021-2317 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-844m-cpr9-jcmh (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2021-41263)Record last updated .