Probo saferedirect CVE-2026-49820
MEDIUM
GHSA-x7qq-m748-8p2c
Severity by source
AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
Network-delivered redirect requiring victim click; no attacker auth needed; scope changes to victim browser; integrity-only impact via host-separator bypass.
Primary rating from GitHub Advisory.
CVSS VectorGitHub Advisory
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
Lifecycle Timeline
1DescriptionGitHub Advisory
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 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.
Workarounds
No practical workaround for self-hosted installations. Upgrade to the patched release.
AnalysisAI
Open redirect in Probo's saferedirect package allows unauthenticated remote attackers to bypass same-origin URL validation across all authentication flows - OIDC, SAML, session transfer, OAuth connectors, and trust-center magic links. A crafted URL such as /../\evil.com passes the flawed second-character check, and Go's http.Redirect normalizer collapses it to /\evil.com before setting the Location header; browsers then interpret the backslash as a host separator and navigate victims to an attacker-controlled domain. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | A victim user must click a specially crafted link containing a malicious redirect parameter - user interaction (UI:R per CVSS) is mandatory and passive server-side exploitation is not possible. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 score of 4.7 (AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N) accurately reflects a moderate-severity open redirect: network-reachable, trivially exploitable, no authentication required, but contingent on victim interaction and producing only integrity impact. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker crafts a phishing email containing a Probo login URL with a malicious continue parameter, e.g., https://auth.probo.example.com/login?continue=/../%5cevil.com. A target user clicks the link, completes normal authentication against the legitimate Probo domain, and is silently redirected by the browser to the attacker-controlled site - which may mirror the Probo UI to harvest credentials or session cookies. … |
| Remediation | Self-hosted deployments must upgrade to probod v0.194.1 or later, available from the upstream repository at https://github.com/getprobo/probo. … Detailed patch versions, workarounds, and compensating controls in full report. |
Threat intelligence, references, and detailed analysis are available after sign-in.
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