CVE-2026-102877: Fider before 0.38.0 SSRF via DNS rebinding in webhook validation

Severity: medium (CVSS 4.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-29 · updated 2026-09-30
Weakness: CWE-918

Description

Fider before 0.38.0 contains a server-side request forgery vulnerability due to a time-of-check time-of-use gap in URL validation for webhooks and custom OAuth provider endpoints. Administrators controlling DNS can perform DNS rebinding attacks to make the Fider server send requests to internal services or cloud metadata endpoints.

Affected products

getfider fider: before 0.38.0 — fixed in 0.38.0

How to fix

Upgrade to a fixed version: getfider fider 0.38.0. Check the vendor advisory for mitigations.

References

https://github.com/getfider/fider
https://github.com/getfider/fider/blob/v0.37.0/app/pkg/validate/general.go
https://github.com/getfider/fider/blob/v0.37.0/app/services/httpclient/httpclient.go
https://github.com/getfider/fider/commit/45f5627b9fd15b912fb9092635c863fb4c91dd69
https://github.com/getfider/fider/releases/tag/v0.38.0
https://github.com/getfider/fider/security/advisories/GHSA-whx4-hxwq-qgjh
https://www.vulncheck.com/advisories/fider-before-0.38.0-ssrf-via-dns-rebinding-in-webhook-validation

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