# CVE-2026-49826: Concourse CI open redirect in login flow

Source: https://junglewise.ai/threats/cve-2026-49826-concourse-ci-open-redirect-in-login-flow  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-01. Updated: 2026-07-01  
License: CC BY 4.0 with a link back

CVE-2026-49826 · Severity: medium · CVSS 4 · Published 2026-07-01

Concourse CI, an open-source continuous integration tool, is vulnerable to an open redirect issue during its login process. An attacker can trick users into clicking a specially crafted link that, after a successful login, redirects them to a malicious external website. This technique is commonly used in phishing campaigns to deceive users into providing credentials to a fraudulent site that mimics the legitimate service.

Technologies: [github.com/concourse/concourse (Go)](https://junglewise.ai/threats/technologies/github-com-concourse-concourse). Vendors: [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-49826 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-49826 being exploited in the wild.

**How severe is CVE-2026-49826?** Medium severity, with a CVSS score of 4, published 1 July 2026.

**Which products and versions are affected?** Concourse CI < 8.2.3; github.com/concourse/concourse (Go) < 1.6.1-0.20260526150512-ac60be5f0435, SEMVER:introduced=0,fixed=1.6.1-0.20260526150512-ac60be5f0435.

**Is there a fix for CVE-2026-49826?** Yes. github.com/concourse/concourse (Go): upgrade to 1.6.1-0.20260526150512-ac60be5f0435 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-49826 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-49826?** Check whether you run Concourse CI or github.com/concourse/concourse (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/concourse/concourse (Go): upgrade to 1.6.1-0.20260526150512-ac60be5f0435 or later

  ```sh
  go get github.com/concourse/concourse@v1.6.1-0.20260526150512-ac60be5f0435
  ```


## Technical details

An open redirect vulnerability exists in Concourse CI's login flow due to improper handling of the 'redirect_uri' parameter. The root cause is related to how Go's 'url' package processes encoded characters; specifically, double-encoding or including backslashes can bypass path validation logic, causing a relative path like '/%2Fexample.com' to be interpreted as an absolute URL '//example.com'. An unauthenticated attacker can craft a URL that redirects a user to an arbitrary external site after they complete the login process. This issue is fixed in Concourse version 8.2.3.

## Affected products

- Concourse Concourse CI < 8.2.3

## Identifiers

- CVE-2026-49826
- GHSA-8w27-c4vc-88q9
- GO-2026-5866

## Timeline

- 2026-05-27: disclosed
- 2026-07-01: advisory: GitHub Advisory published
- 2026-07-01: patched: Fix confirmed in version 8.2.3

## References

- [https://api.github.com/users/Fushuling](https://api.github.com/users/Fushuling)
- [https://github.com/Fushuling](https://github.com/Fushuling)
- [https://api.github.com/users/Fushuling/gists%7B/gist_id%7D](https://api.github.com/users/Fushuling/gists%7B/gist_id%7D)
- [https://api.github.com/users/Fushuling/repos](https://api.github.com/users/Fushuling/repos)
- [https://avatars.githubusercontent.com/u/98574309?v=4](https://avatars.githubusercontent.com/u/98574309?v=4)
- [https://api.github.com/users/Fushuling/events%7B/privacy%7D](https://api.github.com/users/Fushuling/events%7B/privacy%7D)

## Related threats

- [Team scope authorization bypass when Post/Put request with :team_name in body, allows HTTP parameter pollution](https://junglewise.ai/threats/cve-2022-31683-team-scope-authorization-bypass-when-post-put-request-with-team)
- [Pivotal Concourse SQL Injection Vulnerability](https://junglewise.ai/threats/cve-2019-3792-pivotal-concourse-sql-injection-vulnerability)
- [Pivotal Concourse Open Redirect in Login Flow](https://junglewise.ai/threats/cve-2018-15798-pivotal-concourse-open-redirect-in-login-flow)
- [GitLab auth uses full name instead of username as user ID, allowing impersonation](https://junglewise.ai/threats/cve-2020-5415-gitlab-auth-uses-full-name-instead-of-username-as-user-id-allowing)