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Fencer Vulns
high 8.1

CVE-2021-28680 json

Improper Privilege Management in devise_masquerade

published 2021-12-07 4 y ago modified 2026-06-17 4 mo ago also GHSA-25f5-gc4h-hc22 , EUVD-2021-2418

cvss
8.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.3%
EPSS 1.3% chance of exploitation in 30 days, percentile 69%
public exploits
0
none known

Summary

The devise_masquerade gem before 1.3 allows certain attacks when a password's salt is unknown. An application that uses this gem to let administrators masquerade/impersonate users loses one layer of security protection compared to a situation where Devise (without this extension) is used. If the server-side secret_key_base value became publicly known (for instance if it is committed to a public repository by mistake), there are still other protections in place that prevent an attacker from impersonating any user on the site. When masquerading is not used in a plain Devise application, one must know the password salt of the target user if one wants to encrypt and sign a valid session cookie. When devise_masquerade is used, however, an attacker can decide which user the "back" action will go back to without knowing that user's password salt and simply knowing the user ID, by manipulating the session cookie and pretending that a user is already masqueraded by an administrator.

Patch / fix

  • rubygems devise_masquerade 1.3.1
  • devise_masquerade_project devise_masquerade 1.3.0

Exploit prediction

1.25% chance of exploitation in the next 30 days, higher than 69% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • labanskoller.se https://labanskoller.se/blog/2021/03/23/the-devise-extension-that-peeled-off-one-layer-of-the-security-onion-cve-2021-28680/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 8.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P
GitHub 3.1 8.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
rubygems devise_masquerade
<1.3.1
1.3.1

Classification

Weakness
  • CWE-269 Improper Privilege Management

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.