Probo has an open redirect bypass via path normalization

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

4.7 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N

EPSS

• CVE-2026-49820: 0.42% estimated exploitation activity in the next 30 days; percentile 36.08 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact Probo's saferedirect package validates redirect URLs used across authentication flows (OIDC, SAML, session transfer, OAuth connectors, and trust-center magic links). The validator only inspected the second character of relative paths, so a URL like /../\evil.com passed validation because the second character is .. Go's http.Redirect normalizes this path to /\evil.com before setting the Location header. Browsers can interpret the backslash as a host separator and redirect the user to an external domain (https://evil.com), bypassing the intended same-origin restriction. This enables open-redirect phishing: an attacker can craft a continue parameter (or embed a malicious URL in a session-transfer token) that appears to originate from a trusted Probo domain but redirects victims elsewhere. Patches Fixed in go.probo.inc/probo by normalizing relative paths with path.Clean before validation, rejecting backslashes (including percent-encoded %5c) anywhere in the path, and re-checking…

Published by the source

30 Jun 2026, 18:31 UTC

Last modified by the source

30 Jun 2026, 18:31 UTC

Source last checked

26 Oct 2026, 15:24 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-x7qq-m748-8p2c

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# Patch Next advisory brief: CVE-2026-49820

Advisory: Probo has an open redirect bypass via path normalization
IDs: CVE-2026-49820, GHSA-x7qq-m748-8p2c
Record: https://patchnext.com/advisories/cve-2026-49820 (revision 1, source checked 26 Oct 2026, 15:24 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: go.probo.inc/probo 0.204.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go go.probo.inc/probo: affected < 0.204.0; fixed in 0.204.0

## Suggested inspection (read-only)
- Go go.probo.inc/probo: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on go.probo.inc/probo.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-x7qq-m748-8p2c (GitHub-reviewed advisory GHSA-x7qq-m748-8p2c lists affected ranges: Go go.probo.inc/probo >=0 <0.204.0)

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