CVE-2026-49826Public exploitNetwork attack vectorHinoki check available

Post-login open redirect via stacked URL decoding

Published Aug 14, 2026 · Updated Aug 14, 2026

Open redirect in Concourse before 8.2.3 allows remote attackers to send users to an arbitrary site through a crafted login URL. The SkyServer Redirect method parses a slash-trimmed redirect_uri before fully decoding stacked escapes, allowing an encoded slash and backslash to become a protocol-relative external URL. A user must follow the crafted URL and complete the login flow; the flaw then redirects the browser but does not directly disclose credentials.

CVSS severity0.0
None
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Open redirect in Concourse before 8.2.3 allows remote attackers to send users to an arbitrary site through a crafted login URL. The SkyServer Redirect method parses a slash-trimmed redirect_uri before fully decoding stacked escapes, allowing an encoded slash and backslash to become a protocol-relative external URL. A user must follow the crafted URL and complete the login flow; the flaw then redirects the browser but does not directly disclose credentials.

The record

CVE
CVE-2026-49826
Published
Aug 14, 2026
Updated
Aug 14, 2026
Vendor
Pivotal Software
Product
Concourse
Classifications
CWE-601, CAPEC-178, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 8.2.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Pivotal Software · Concourseversion=< 8.2.3

Published CVSS scores

0.0GitHubCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-601URL Redirection to Untrusted Site ('Open Redirect')
CAPEC-178Cross-Site Flashing
T1204.001User Execution: Malicious Link

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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