CVE-2026-35404 openedx · openedx

Open edX Platform has an Open Redirect in Survey Views via Unvalidated redirect_url Parameter

Vulnerability at a glance

Severity, exploitation likelihood & attack requirements

CVSS v3.1 severity
6.1Medium
EPSS · exploitation likelihood
0.223% Probability within 30 daysPercentile 12.8
EPSS trend
Down 0.034 pp Since 2026-10-19 · percentage points
Known exploitation
Not in KEV CISA KEV catalog Absence does not establish safety
Attack vector
NetworkRemotely reachable
Attack complexity
LowFewer obstacles to exploitation
Privileges required
NoneNo authentication required
User interaction
RequiredUser action required
Exploit availability & maturity
Not scored Exploit reference available No explicit exploit maturity assessment View exploit evidence
How to read the colors & trend
Higher exposureElevatedModerateLower exposureUnknown / unassessed

CVSS colors follow its reported severity. Attack-factor colors describe each requirement, not an overall risk rating. Gray also covers absence from KEV; absence does not establish safety.

EPSS display bands: below 1% blue, 1–10% amber, 10–50% orange, 50% and above red. These are presentation bands, not FIRST severity categories. The trend compares daily EPSS probabilities, not percentile ranks; “pp” means percentage points. The sparkline shows relative movement, with its vertical scale fitted to the observed scores.

Already protected by existing Atomicorp rules No new CVE-specific rule required.

Atomicorp ModSecurity protection

Protected by Atomicorp rules

Atomicorp ModSecurity rules block attacks exploiting this vulnerability. Keep your rules current.

By targeting underlying attack techniques and CWE weakness classes, existing rules can protect against newly disclosed vulnerabilities. Rule changes are regression-tested against attack and false-positive corpora.

1 rule identified Verified 2026-09-06 View rules & research details →

WAF protection does not change the CVSS or EPSS score. Keep your software patched and your Atomicorp rules current.

CISA SSVC assessment

CISA ADP · Assessed 2026-04-07 · SSVC 2.0.3

Exploitation
Proof-of-concept
Automatable
No
Technical Impact
Partial

Stakeholder-Specific Vulnerability Categorization records CISA’s assessment of exploitation, automation, and technical impact. “None reported” reflects the assessment date; it does not establish that no exploit exists. View SSVC source details.

On this page

CVE Details

  • Protection status: Protected by Atomicorp rules · About protection statuses
  • CVE: CVE-2026-35404
  • Name: Open edX Platform has an Open Redirect in Survey Views via Unvalidated redirect_url Parameter
  • Severity: Medium
  • CVSS: 6.1 (v3.1) (Medium)
  • CVSS version: 3.1
  • CVSS source: NVD
  • CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
    • Attack vector: Network
    • Attack complexity: Low
    • Privileges required: None
    • User interaction: Required
    • Scope: Changed
    • Confidentiality impact: Low
    • Integrity impact: Low
    • Availability impact: None
  • CWE: CWE-601 — URL Redirection to Untrusted Site (‘Open Redirect’)
  • Related CAPEC attack patterns (via MITRE CWE relationships): CAPEC-178
  • Vendor: openedx
  • Vulnerable product: openedx
  • CVE published: 2026-04-06
  • CVE last modified: 2026-07-24
  • Affected versions (NVD configurations):
    • openedx: <= 2026-04-02
  • EPSS: 0.0022; 12.8th percentile as of 2026-10-26 (FIRST )
  • Latest Update: 2026-09-06
  • Selected Rule IDs observed: 344365
  • Matching rules: 1; rules with blocking actions: 1
  • Would-block Rule IDs: 344365
  • Request surfaces inspected: JSON request data, Request URI, Request argument names, Request arguments, Request headers, SOAP request data
Technical vulnerability details · CVSS assessments, exploit evidence & CPE data

CVSS assessments

CVSS v3.1 · security-advisories@github.com

  • Base score: 4.7
  • Base severity: MEDIUM
  • Exploitability subscore: 2.8
  • Impact subscore: 1.4
  • Assessment type: Secondary
  • Source identifier: security-advisories@github.com
  • Full vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N
    • Attack vector: Network
    • Attack complexity: Low
    • Privileges required: None
    • User interaction: Required
    • Scope: Changed
    • Confidentiality impact: Low
    • Integrity impact: None
    • Availability impact: None
  • Exploit maturity: Not scored

CVSS v3.1 · NVD

  • Base score: 6.1
  • Base severity: MEDIUM
  • Exploitability subscore: 2.8
  • Impact subscore: 2.7
  • Assessment type: Primary
  • Source identifier: nvd@nist.gov
  • Full vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
    • Attack vector: Network
    • Attack complexity: Low
    • Privileges required: None
    • User interaction: Required
    • Scope: Changed
    • Confidentiality impact: Low
    • Integrity impact: Low
    • Availability impact: None
  • Exploit maturity: Not scored

Exploitability and impact subscores describe the vulnerability’s technical characteristics. Exploit maturity describes the reported state of exploitation; these are separate measures.

Assessment source: NVD record · CVE record

CISA SSVC assessments

These are CISA’s published decision points at the assessment time. They are not a complete organization-specific prioritization decision.

  • Provider: CISA ADP
  • Provider identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  • SSVC version: 2.0.3
  • Role: CISA Coordinator
  • Assessment timestamp: 2026-04-07T16:17:36.155139Z
  • Exploitation: poc
  • Automatable: no
  • Technical Impact: partial
  • Source: CISA ADP in the CVE record

Exploit references

The CVE source data tags these references as exploits. A reference alone does not establish reliability or active exploitation.

Vulnerable CPE configurations

  • cpe:2.3:a:openedx:openedx:*:*:*:*:*:*:*:*
    • Version end (inclusive): 2026-04-02
    • NVD match criteria ID: 06A17A40-548D-40D0-BD7F-CC30B7EA25DA

Vulnerability Description

Open edX Platform enables the authoring and delivery of online learning at any scale. The view_survey endpoint accepts a redirect_url GET parameter that is passed directly to HttpResponseRedirect() without any URL validation. When a non-existent survey name is provided, the server issues an immediate HTTP 302 redirect to the attacker-controlled URL. Additionally, the same unvalidated URL is embedded in a hidden form field and returned in a JSON response after form submission, where client-side JavaScript performs location.href = url. This enables phishing and credential theft attacks against authenticated Open edX users. This vulnerability is fixed with commit 76462f1e5fa9b37d2621ad7ad19514b403908970.

  1. Maintain the observed Atomicorp protections. Keep your Atomicorp commercial rules current and confirm that the selected observed rules (344365 ) have not been locally disabled. Atomicorp commercial rules are enabled by default. If you use Atomic WAF, review the applicable policy and rule settings.

  2. Apply the vendor’s remediation. WAF protection is defense in depth and does not replace upgrading or following the affected vendor’s guidance.

    • Affected versions: openedx openedx-platform version < 76462f1e5fa9b37d2621ad7ad19514b403908970.
    • The CVE record does not include written upgrade or workaround instructions, but it does publish the following patch or mitigation reference:

  3. Validate after changes. Confirm rule updates are current, review WAF events for the affected application, and test application behavior after vendor upgrades, mitigations, or local policy changes.

Research Notes

Atomicorp WAF protections are designed around attack techniques and exploit behaviors, allowing existing protections to apply across multiple vulnerabilities without requiring a unique rule for every CVE.

Public Vulnerability References

Test or Research Source

  • Source: Atomicorp AI Research Framework
  • Tags: cve, derived, redirect, waf-probe

Research Note Context

This research note documents exploit-technique analysis associated with this vulnerability and references Atomicorp WAF protections observed during engineering review, testing, or validation activities.

Atomicorp security controls are generally designed to identify and mitigate attack techniques and exploit behaviors rather than individual CVE identifiers. As a result, protections developed for one vulnerability may also apply to related attack variants and future vulnerabilities using similar techniques.

Learn More

Atomicorp develops commercially supported security technologies for web applications, servers, endpoints, workloads, and legacy enterprise platforms.

Organizations interested in protecting systems against exploit techniques associated with vulnerabilities such as this one can learn more about:

  • Atomic ModSecurity Rules: commercially maintained WAF rules for ModSecurity deployments, including protections for web attacks, bots, scanners, malware, exploitation attempts, and emerging vulnerability classes.
  • Atomic WAF: an enterprise web application firewall with Atomicorp rules, centralized management, reporting, authentication controls, and operational tooling.
  • Atomic ModSecurity Integrator: a special licensing option for MSPs, MSSPs, OEMs, VARs, reverse proxy providers, and other integrators who want to incorporate Atomicorp ModSecurity rule technology into their own products or services.
  • Atomic OSSEC: an enterprise OSSEC-based intrusion detection, compliance, and security monitoring platform.
  • Atomic Protector: workload protection for Linux, web, cloud, data center, and hybrid environments.

For additional information, product evaluations, or technical discussions, visit https://www.atomicorp.com/ or https://modsecurity.io/ .