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CVE-2026-28413

Products.isurlinportal: Possible open redirect when using more than 2 forward slashes

5.3 MediumFix available

Products.isurlinportal is a replacement for isURLInPortal method in Plone. Prior to versions 2.1.0, 3.1.0, and 4.0.0, a url /login?came_from=////evil.example may redirect to an external website after login. This issue has been patched in versions 2.1.0, 3.1.0, and 4.0.0.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
Low
Integrity
None
Availability
None

Exploit likelihood

0.26%Up 0.2 points since Mar 6, 2026
90%50%10%1%

What each source reports

CVE List Score used 5.3

Products.isurlinportal: Possible open redirect when using more than 2 forward slashes

Products.isurlinportal is a replacement for isURLInPortal method in Plone. Prior to versions 2.1.0, 3.1.0, and 4.0.0, a url /login?came_from=////evil.example may redirect to an external website after login. This issue has been patched in versions 2.1.0, 3.1.0, and 4.0.0.

Record
CVE-2026-28413
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-601
Updated
2026-11-02
EUVDEUVD-2026-9872 5.3

Products.isurlinportal is a replacement for isURLInPortal method in Plone. Prior to versions 2.1.0, 3.1.0, and 4.0.0, a url /login?came_from=////evil.example may redirect to an external website after login. This issue has been patched in versions 2.1.0, 3.1.0, and 4.0.0.

Record
EUVD-2026-9872
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-43gx-6gv6-3jcp 5.3

Products.isurlinportal has possible open redirect when using more than 2 forward slashes

Impact

A url /login?came_from=////evil.example may redirect to an external website after login.

Standard Plone is not affected, but if you have customised the login, for example with add-ons, you might be affected. You can try the url to check if you are affected or not.

Patches

The problem has been patched in Products.isurlinportal.

  • Plone 6.2: upgrade to Products.isurlinportal 4.0.0.
  • Plone 6.1: upgrade to Products.isurlinportal 3.1.0.
  • Plone 6.0: upgrade to Products.isurlinportal 2.1.0.
  • Older Plone versions don't have security support anymore.

Workarounds

There are no known workarounds.

Background

When you are anonymous and land on a page that requires a login, Plone sends you to the login form. After successful login, Plone redirects you back to the page you came from. Various other forms and pages have a similar system.

This could get abused by an attacker to trick Plone into redirecting to a different website. Plone checks the page that would be redirected to. It is only accepted if it is within the Plone site domain or part of a different trusted domain.

The main check for this is in the Products.isurlinportal package. A lot of potentially malicious urls are already safely rejected, but here a loop hole was found.

This was discovered during a penetration test by the CERT-EU Team.

Record
GHSA-43gx-6gv6-3jcp
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-601
Updated
2026-11-02
NVD 5.3

Products.isurlinportal is a replacement for isURLInPortal method in Plone. Prior to versions 2.1.0, 3.1.0, and 4.0.0, a url /login?came_from=////evil.example may redirect to an external website after login. This issue has been patched in versions 2.1.0, 3.1.0, and 4.0.0.

Record
CVE-2026-28413
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weakness
CWE-601
Updated
2026-11-02
OSV 5.3

Products.isurlinportal: Possible open redirect when using more than 2 forward slashes

Products.isurlinportal is a replacement for isURLInPortal method in Plone. Prior to versions 2.1.0, 3.1.0, and 4.0.0, a url /login?came_from=////evil.example may redirect to an external website after login. This issue has been patched in versions 2.1.0, 3.1.0, and 4.0.0.

Record
CVE-2026-28413
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-601
Updated
2026-11-02
OSVGHSA-43gx-6gv6-3jcp 5.3

Products.isurlinportal has possible open redirect when using more than 2 forward slashes

Impact

A url /login?came_from=////evil.example may redirect to an external website after login.

Standard Plone is not affected, but if you have customised the login, for example with add-ons, you might be affected. You can try the url to check if you are affected or not.

Patches

The problem has been patched in Products.isurlinportal.

  • Plone 6.2: upgrade to Products.isurlinportal 4.0.0.
  • Plone 6.1: upgrade to Products.isurlinportal 3.1.0.
  • Plone 6.0: upgrade to Products.isurlinportal 2.1.0.
  • Older Plone versions don't have security support anymore.

Workarounds

There are no known workarounds.

Background

When you are anonymous and land on a page that requires a login, Plone sends you to the login form. After successful login, Plone redirects you back to the page you came from. Various other forms and pages have a similar system.

This could get abused by an attacker to trick Plone into redirecting to a different website. Plone checks the page that would be redirected to. It is only accepted if it is within the Plone site domain or part of a different trusted domain.

The main check for this is in the Products.isurlinportal package. A lot of potentially malicious urls are already safely rejected, but here a loop hole was found.

This was discovered during a penetration test by the CERT-EU Team.

Record
GHSA-43gx-6gv6-3jcp
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-601
Updated
2026-11-02
OSVPYSEC-2026-112 6.1

Products.isurlinportal is a replacement for isURLInPortal method in Plone. Prior to versions 2.1.0, 3.1.0, and 4.0.0, a url /login?came_from=////evil.example may redirect to an external website after login. This issue has been patched in versions 2.1.0, 3.1.0, and 4.0.0.

Record
PYSEC-2026-112
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
products-isurlinportal
PyPI
 4.0.0a1 to 4.0.0a1
4.0.0
products-isurlinportal
PyPI
 3.0.0 up to 3.1.0
3.1.0
products-isurlinportal
PyPI
 before 2.1.0
2.1.0
products-isurlinportal
PyPI
 4.0.0a1 up to 4.0.0
4.0.0
products-isurlinportal
PyPI
 3.0.0 up to 3.1.0, plus listed versions
3.0.1
3.1.0
products-isurlinportal
PyPI
 before 2.1.0, plus listed versions
1.0.01.1.01.1.11.2.01.2.1
Show 4 moreShow less
2.0.02.0.12.0.22.0.3
2.1.0
products-isurlinportal
PyPI
 before 2.1.0, 3.0.0 up to 3.1.0, plus listed versions
1.0.01.1.01.1.11.2.01.2.1
Show 5 moreShow less
2.0.02.0.12.0.22.0.33.0.1
2.1.03.1.0

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-28413 is a medium vulnerability (CVSS 5.3) in Plone Isurlinportal, published March 2, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.26%, the 17th percentile. Fixed in products-isurlinportal 4.0.0.

References

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