CVE-2026-49820 — probo
MEDIUMCVE-2026-49820 is a medium-severity (CVSS 4.7) Open Redirect vulnerability in go.probo.inc/probo. A fix is available for go.probo.inc/probo — see the affected versions and patch details below.
Probo has an open redirect bypass via path normalization
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-49820.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-49820 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 380,526 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
go.probo.inc/proboReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | go.probo.inc/probo | all versions | 0.204.0go get go.probo.inc/probo@v0.204.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for go.probo.inc/probo, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update go.probo.inc/probo to 0.204.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-49820 is resolved across your whole dependency graph.
Workarounds
Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.
Frequently Asked Questions
Is CVE-2026-49820 in your dependencies?
Find it across Go, including transitive dependencies.