BIT-concourse-2026-49826Published

Concourse login flow has an open redirect issue

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cve-program · CVE-2026-49826

Published

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.

Source published: 14 Aug 2026 16:25:56 UTC
Source modified: 14 Aug 2026 18:06:17 UTC
Saved here: 23 Oct 2026 15:48:27 UTC
Source terms: CVE Program Terms of Use

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CVSS 4.0 · 0.0 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

euvd · EUVD-2026-58716

Published

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EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON.

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datePublished: Aug 14, 2026, 4:25:56 PM

dateUpdated: Aug 14, 2026, 6:06:17 PM

Source published: Aug 14, 2026, 4:25:56 PM (timezone not stated)
Source modified: Aug 14, 2026, 6:06:17 PM (timezone not stated)
Saved here: 11 Nov 2026 14:09:31 UTC
Source terms: ENISA EUVD · source terms and attribution apply

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nvd · CVE-2026-49826

Published

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NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.

Source analysis status: Awaiting Analysis

Weakness classifications: CWE-601

Original publisher date fields

published: 2026-08-14T17:18:27.007

lastModified: 2026-09-18T20:05:53.723

Source published: 14 Aug 2026 17:18:27 UTC
Source modified: 18 Sep 2026 20:05:53 UTC
Saved here: 25 Oct 2026 12:17:38 UTC
Source terms: NIST NVD usage terms; underlying source attribution retained

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CVSS 4.0 · [email protected] · Secondary · 0.0 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

osv · GHSA-8w27-c4vc-88q9

Published

### Impact 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. ### Patches This has been fixed in 8.2.3 ### Workarounds None. ### Exploit Vulnerable code was in: https://github.com/concourse/concourse/blob/ea7b812e3a88fdd070f0faece874e8a2d4fbb31c/skymarshal/skyserver/skyserver.go#L162-L170 The issue stems from the underlying processing logic of Go's `url` package. Normally, `ParseRequestURI()` will eventually reach an internal `url.setPath()` function, where the URL will be decoded. However, if `RawPath` is not empty and `validEncoded(RawPath)` is true, and the decoded result equals `Path`, then return `RawPath` as is; otherwise, escape `Path` again, i.e., decode it again. In other words, if the URL contains dangerous characters that should be escaped, such as backslashes (`\`), then an extra decoding step will be performed. Therefore, `/%2Fexample.com` will be parsed as `//example.com`. On vulnerable versions of Concourse, add `/sky/login?redirect_uri=/%252Fexample.com/\` to your Concourse external URL, login as usual, and you should be redirected to `example.com` instead of your Concourse web server. The redirect happens after the login flow completes. No credentials are leaked.

Source published: 1 Jul 2026 19:01:16 UTC
Source modified: 19 Aug 2026 09:55:28 UTC
Saved here: 24 Oct 2026 13:19:41 UTC
Source terms: GitHub Advisory Database · CC-BY-4.0

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CVSS_V4 · 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

Publisher rating · LOW

osv · GO-2026-5866

Published

Concourse login flow has an open redirect issue in github.com/concourse/concourse

Source published: 7 Jul 2026 15:26:37 UTC
Source modified: 19 Aug 2026 09:55:28 UTC
Saved here: 24 Oct 2026 13:19:41 UTC
Source terms: OSV · upstream source license applies

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Source: osv · OSV · upstream source license applies. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.