CVE-2026-28413Public exploitNetwork attack vector

Open redirect via excess leading slashes

Published Mar 5, 2026 · Updated Mar 5, 2026

Open redirect in Plone Products.isurlinportal before 2.1.0, 3.1.0, and 4.0.0 allows remote attackers to send browsers off-site. The isURLInPortal method wrongly treats came_from URLs beginning with more than two forward slashes as being inside the Plone site. Standard Plone is unaffected; exposure requires a customized login flow, such as an add-on, that redirects to the accepted came_from value after login.

CVSS severity5.3
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 Plone Products.isurlinportal before 2.1.0, 3.1.0, and 4.0.0 allows remote attackers to send browsers off-site. The isURLInPortal method wrongly treats came_from URLs beginning with more than two forward slashes as being inside the Plone site. Standard Plone is unaffected; exposure requires a customized login flow, such as an add-on, that redirects to the accepted came_from value after login.

The record

CVE
CVE-2026-28413
Published
Mar 5, 2026
Updated
Mar 5, 2026
Vendor
Plone
Product
Products.isurlinportal
Classifications
CWE-601, CAPEC-178, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 5, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=< 2.1.0
  2. Affected versionversion=< 3.1.0
  3. Affected versionversion=< 4.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Plone · Products.isurlinportalversion=< 2.1.0; version=< 3.1.0; version=< 4.0.0

Published CVSS scores

5.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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.

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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