CVE-2026-42259

Saltcorn: Open Redirect in `POST /auth/login` due to incomplete `is_relative_url` validation (backslash bypass)

State: Published
Severity: 5.1 Medium
Published: May 7, 2026
Updated: May 8, 2026
Reserved: Apr 26, 2026

Description

Saltcorn is an extensible, open source, no-code database application builder. Prior to versions 1.4.6, 1.5.6, and 1.6.0-beta.5, Saltcorn validates the post-login dest parameter with a string check that only blocks :/ and //. Because all WHATWG-compliant browsers normalise backslashes (\) to forward slashes (/) for special schemes, a payload such as /\evil.com/path slips through is_relative_url(), is emitted unchanged in the HTTP Location header, and causes the browser to navigate cross-origin to an attacker-controlled domain. The bug is reachable on a default install and only requires a victim who can be tricked into logging in via a crafted Saltcorn URL. This issue has been patched in versions 1.4.6, 1.5.6, and 1.6.0-beta.5.

Scores

CVSS	Score	Vector	Source
4.0	5.1 Medium	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N	GitHub_M

Weaknesses

CWE-601 URL Redirection to Untrusted Site ('Open Redirect')

Affected Products

Product	Versions
saltcornsaltcorn	< 1.4.6Affected >= 1.5.0-beta.0, < 1.5.6Affected >= 1.6.0-alpha.0, < 1.6.0-beta.5Affected

References

https://github.com/saltcorn/saltcorn/security/advisories/GHSA-f3g8-9xv5-77gv

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