CVE-2026-49820 Probo has an open redirect bypass via path normalization
Attackers can bypass redirect validation to send users to malicious sites via crafted URLs, enabling phishing attacks against Probo users.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-49820?
CVE-2026-49820 is a medium-severity vulnerability in getprobo probo, published on 13 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Probo is a self-hostable governance, risk, and compliance (GRC) platform built for engineering and security teams. Probo's `saferedirect` package validates redirect URLs used across authentication flows (OIDC, SAML, session transfer, OAuth connectors, and trust-center magic links). Prior to version 0.19.3.1, 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. This is fixed in `go.probo.inc/probo` 0.193.1 by normalizing relative paths with `path.Clean` before validation, rejecting backslashes (including percent-encoded `%5c`) anywhere in the path, and re-checking the normalized result for protocol-relative and backslash prefixes. Self-hosted deployments should upgrade to probod v0.194.1 or later. SaaS deployments on getprobo.com are patched. No practical workaround is available for self-hosted installations.
Weakness: CWE-601
Which versions are affected by CVE-2026-49820?
3 open source packages ship an affected version, including go.probo.inc/probo.
| Package | Affected | Fixed in |
|---|---|---|
go.probo.inc/probo Go | All versions | 0.204.0 |
go.probo.inc/probo Go | All versions | 0.204.0 |
go.probo.inc/probo Go | All versions | 0.204.0 |
How do I fix CVE-2026-49820?
Upgrade go.probo.inc/probo to 0.204.0 or later.
Is CVE-2026-49820 being exploited?
There is no known exploitation of CVE-2026-49820 in the wild and no public exploit code.
Sources
Also known as GHSA-x7qq-m748-8p2c, GO-2026-5861.