CVE-2025-8129Public exploitNetwork attack vector

Open redirect via unvalidated Referrer header

Published Jul 25, 2025 · Updated Jul 25, 2025

Open redirect in Koa 2.0.0 through 2.16.1 and 3.0.0-alpha.0 through 3.0.0 allows remote authenticated users to redirect clients. The back method in lib/response.js passes the request-controlled Referrer value directly to redirect(), which writes it into the 302 Location header without restricting its origin. Exploitation requires an application route that invokes ctx.back() and a client that follows the returned redirect.

CVSS severity6.1
Medium
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Open redirect in Koa 2.0.0 through 2.16.1 and 3.0.0-alpha.0 through 3.0.0 allows remote authenticated users to redirect clients. The back method in lib/response.js passes the request-controlled Referrer value directly to redirect(), which writes it into the 302 Location header without restricting its origin. Exploitation requires an application route that invokes ctx.back() and a client that follows the returned redirect.

The record

CVE
CVE-2025-8129
Published
Jul 25, 2025
Updated
Jul 25, 2025
Vendor
Koa.js
Product
Koa
Classifications
CWE-601
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 25, 2025CVE publishedPublication date reported by the CVE source.
  2. Jul 25, 2025Record 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=3.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Koa.js · Koaversion=3.0

Published CVSS scores

6.1NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
3.5VulDBCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N
2.0VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/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
4.0VulDBAV:N/AC:L/Au:S/C:N/I:P/A: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.

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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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-601URL Redirection to Untrusted Site ('Open Redirect')

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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