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Fencer Vulns
critical 9.1

CVE-2026-28215 json

hoppscotch Vulnerable to Unauthenticated Onboarding Config Takeover

published 2026-02-26 8 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-8912

cvss
9.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 48%
public exploits
0
none known

Summary

hoppscotch is an open source API development ecosystem. Prior to version 2026.2.0, an unauthenticated attacker can overwrite the entire infrastructure configuration of a self-hosted Hoppscotch instance including OAuth provider credentials and SMTP settings by sending a single HTTP POST request with no authentication. The endpoint POST /v1/onboarding/config has no authentication guard and performs no check on whether onboarding was already completed. A successful exploit allows the attacker to replace the instance's Google/GitHub/Microsoft OAuth application credentials with their own, causing all subsequent user logins via SSO to authenticate against the attacker's OAuth app. The attacker captures OAuth tokens and email addresses of every user who logs in after the exploit. Additionally, the endpoint returns a recovery token that can be used to read all stored secrets in plaintext, including SMTP passwords and any other configured credentials. Version 2026.2.0 fixes the issue.

Patch / fix

  • hoppscotch hoppscotch 2026.2.0

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
8 mo ago

Exploit prediction

0.59% chance of exploitation in the next 30 days, higher than 48% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/hoppscotch/hoppscotch/security/advisories/GHSA-jwv8-867r-q9fg referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

  • hoppscotch hoppscotch

Classification

Weakness

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.