CVE-2026-128043: OpenMage: CSRF in PayPal cancel handlers voids orders

LOW

Published November 13, 2026

CISO Take

OpenMage magento-lts before 20.19.0 and 21.0.0-beta3 has a cross-site request forgery flaw in its PayPal cancel and decline return handlers, which trust only the shopper's checkout session and never verify the request came from PayPal. An attacker can lure a logged-in shopper to a cross-site GET request that cancels their recent uninvoiced order, voids pending authorizations and restores the items to the cart. Impact is low: CVSS 3.1, integrity-only, high attack complexity, user interaction required, no confidentiality or availability impact, not in CISA KEV, no public exploit or Nuclei template, and no EPSS score yet. This is a classic e-commerce flaw with no meaningful AI/ML component, so the 'ai_agent' categorization looks like a false positive and it should be handled as routine patch hygiene. Upgrade to 20.19.0 or 21.0.0-beta3, and prioritize it only if you run OpenMage storefronts with PayPal Standard enabled.

Sources:NVDGitHub AdvisoryVulnCheck

What is the risk?

Low. The attack needs a victim with an active checkout session, a successful cross-site lure (UI:R) and precise timing (AC:H). Only integrity of a single order is affected, with no data disclosure and no service outage. Exploitation likelihood is low: no public exploit, no scanner template, not in KEV, and EPSS is unavailable. Exposure is limited to OpenMage/Magento LTS stores using the PayPal Standard payment flow. There is no direct AI/ML risk.

How does the attack unfold?

Initial Access

The attacker lures a logged-in shopper to a malicious page or link through phishing or a hosted page.

AML.T0078

Exploitation

The victim's browser sends a cross-site GET to paypal/standard/cancel, and the handler trusts the session without verifying PayPal origin.

Impact

The recent uninvoiced order is cancelled, pending authorizations are voided and the items return to the cart.

AML.T0048.000

Initial Access

The attacker lures a logged-in shopper to a malicious page or link through phishing or a hosted page.

AML.T0078

Exploitation

The victim's browser sends a cross-site GET to paypal/standard/cancel, and the handler trusts the session without verifying PayPal origin.

Impact

The recent uninvoiced order is cancelled, pending authorizations are voided and the items return to the cart.

AML.T0048.000

What systems are affected?

Package	Ecosystem	Vulnerable Range	Patched
magento-lts	—	—	No patch

Do you use magento-lts? You're affected.

How severe is it?

CVSS 3.1

3.1 / 10

EPSS

N/A

Exploitation Status

No known exploitation

Sophistication

Moderate

What is the attack surface?

AVNetwork

ACHigh

PRNone

UIRequired

SUnchanged

CNone

ILow

ANone

What should I do?

5 steps

Upgrade OpenMage magento-lts to 20.19.0 or later, or 21.0.0-beta3 or later; the fix is in commit 86c8895d586db61ac7d093ba4e473103a30882c8.
If you cannot patch immediately, consider disabling PayPal Standard or blocking GET requests to paypal/standard/cancel and the decline handler that lack a valid PayPal-originated token at the WAF or reverse proxy.
Detect abuse by reviewing web logs for GET requests to paypal/standard/cancel with an external or empty Referer, followed by unexpected order cancellations.
Review the GHSA-2jfg-wx75-5cc8 advisory for details.
Keep SameSite cookie attributes strict or lax on session cookies to reduce cross-site request exposure.

How is it classified?

Auth BypassSocial EngineeringPluginAML.T0048.000- Financial Harm AML.T0078- Drive-by Compromise

Which compliance frameworks are affected?

This CVE is relevant to:

NIST AI RMF

MANAGE 2.3-Responses to risks of unknown or unmanaged nature

OWASP LLM Top 10

LLM06-Excessive Agency

Frequently Asked Questions

What is CVE-2026-128043?

Is CVE-2026-128043 actively exploited?

No confirmed active exploitation of CVE-2026-128043 has been reported, but organizations should still patch proactively.

How to fix CVE-2026-128043?

1. Upgrade OpenMage magento-lts to 20.19.0 or later, or 21.0.0-beta3 or later; the fix is in commit 86c8895d586db61ac7d093ba4e473103a30882c8. 2. If you cannot patch immediately, consider disabling PayPal Standard or blocking GET requests to paypal/standard/cancel and the decline handler that lack a valid PayPal-originated token at the WAF or reverse proxy. 3. Detect abuse by reviewing web logs for GET requests to paypal/standard/cancel with an external or empty Referer, followed by unexpected order cancellations. 4. Review the GHSA-2jfg-wx75-5cc8 advisory for details. 5. Keep SameSite cookie attributes strict or lax on session cookies to reduce cross-site request exposure.

What systems are affected by CVE-2026-128043?

This vulnerability affects the following AI/ML architecture patterns: E-commerce platforms (OpenMage/Magento LTS), Payment integrations (PayPal Standard).

What is the CVSS score for CVE-2026-128043?

CVE-2026-128043 has a CVSS v3.1 base score of 3.1 (LOW).

What is the AI security impact?

Affected AI Architectures

E-commerce platforms (OpenMage/Magento LTS)Payment integrations (PayPal Standard)

MITRE ATLAS Techniques

AML.T0048.000Financial Harm

AML.T0078Drive-by Compromise

Compliance Controls Affected

NIST AI RMF: MANAGE 2.3

OWASP LLM Top 10: LLM06

What are the technical details?

Original Advisory

OpenMage magento-lts before 20.19.0 and 21.0.0-beta1 before 21.0.0-beta3 contains a cross-site request forgery vulnerability in PayPal cancel and decline return handlers that trust only the checkout session without verifying the request came from PayPal. Attackers can lure a shopper into a cross-site GET to paypal/standard/cancel to cancel their recent uninvoiced order, void pending authorizations, and restore items to the cart.

Exploitation Scenario

An attacker identifies a victim who is mid-checkout on an OpenMage store, for example through a phishing email or a malicious page. The victim, still logged in, opens a page containing a hidden image or link pointing to https://store.example/paypal/standard/cancel. The browser sends the GET request with the victim's session cookie, and the handler trusts the session and cancels the recent uninvoiced order, voids the pending authorization and restores the cart. The attacker gains no data, only disruption, which could be repeated to harass customers or interfere with sales. If an AI shopping agent is browsing on the user's behalf, it could be lured into the same request.

Weaknesses (CWE)

CWE-352Cross-Site Request Forgery

CWE-352 — Cross-Site Request Forgery: The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.

[Architecture and Design] Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482]. For example, use anti-CSRF packages such as the OWASP CSRFGuard. [REF-330] Another example is the ESAPI Session Management control, which includes a component for CSRF. [REF-45]
[Implementation] Ensure that the application is free of cross-site scripting issues (CWE-79), because most CSRF defenses can be bypassed using attacker-controlled script.

Source: MITRE CWE corpus.