CVE-2021-2114

What it actually does

CVE-2021-2114 is a remotely reachable HTTP vulnerability in Oracle Common Applications Calendar within Oracle E-Business Suite versions 12.1.1 through 12.1.3 and 12.2.3 through 12.2.10. It can be exploited by an unauthenticated network attacker, but exploitation requires interaction by another user, such as following a crafted link or loading attacker-controlled content. Successful exploitation can cross product boundaries within the Oracle E-Business Suite context and may allow unauthorized read access to critical calendar-accessible data, potentially complete access to data exposed through the affected component, and limited unauthorized modification, insertion, or deletion of data.

Why it matters to the business

An attacker may be able to trick a user into triggering unauthorized access or changes inside Oracle E-Business Suite calendar functionality, exposing sensitive business data and potentially altering operational records. Because Oracle E-Business Suite commonly supports finance, HR, procurement, and operational workflows, compromise of one component can create broader business risk even when the vulnerable code is in the calendar module. The EPSS score is high at approximately 0.59 and has remained stable over the last 30 days, indicating meaningful likelihood of exploitation despite the issue not being listed in CISA KEV and no ransomware association being reported.

How an attack unfolds

An attacker identifies an Oracle E-Business Suite instance exposing the affected Oracle Common Applications Calendar functionality over HTTP or HTTPS. The attacker then crafts a malicious request, link, page, or form that targets vulnerable calendar behavior. Because no attacker authentication is required, the attacker’s main dependency is persuading a legitimate user to interact with the crafted content, for example by clicking a link or visiting a page while authenticated to the application. When the user interaction occurs, the vulnerable calendar component processes the attacker-controlled HTTP input in the user/application context, allowing the attacker to obtain unauthorized access to sensitive calendar-accessible data and, in some cases, perform limited unauthorized data changes. Since the CVSS scope is changed, the impact may extend beyond the immediate calendar component into other Oracle E-Business Suite functionality reachable through the affected context.

How to fix it

Apply the Oracle Critical Patch Update that fixes CVE-2021-2114 for Oracle E-Business Suite, or a later Oracle CPU containing the fix, to all affected Oracle Common Applications Calendar deployments. The affected version ranges are Oracle E-Business Suite 12.1.1 through 12.1.3 and 12.2.3 through 12.2.10. If patching cannot be completed immediately, reduce exposure by restricting Oracle E-Business Suite access to trusted networks or VPN, enforcing strong authentication and session protections, disabling or limiting access to unused calendar functionality where feasible, and deploying WAF rules to block suspicious cross-site or malformed requests to E-Business Suite calendar endpoints. Because exploitation requires user interaction, also reinforce phishing-resistant controls, safe-link handling, and user awareness for links targeting Oracle E-Business Suite.

How to confirm the fix worked

Confirm the installed Oracle E-Business Suite release and applied Oracle CPU level against Oracle’s advisory for CVE-2021-2114. Validate that all application tiers and cloned, test, disaster-recovery, and externally exposed instances have the relevant patch applied, not only the primary production instance. Review Oracle OPatch, ADOP, application patch history, and Oracle E-Business Suite patch inventory to verify successful application. From an exposure perspective, confirm that affected calendar functionality is not reachable from untrusted networks unless explicitly required. Perform authenticated application regression testing for calendar read and write workflows after patching, and use a vulnerability scanner or manual version validation to ensure the instance no longer reports an affected Oracle E-Business Suite version or missing CPU.

Typical attack path

1. Discover an internet-facing or internally reachable Oracle E-Business Suite instance running an affected Oracle Common Applications Calendar version.
2. Identify that the target release falls within 12.1.1-12.1.3 or 12.2.3-12.2.10 and has not received the relevant Oracle security patch.
3. Craft malicious HTTP content that targets the vulnerable calendar component.
4. Deliver the crafted link, page, or request trigger to a legitimate user through phishing, chat, documentation links, or another social-engineering channel.
5. Wait for the user to interact with the malicious content while able to reach or authenticate to Oracle E-Business Suite.
6. Leverage the vulnerable processing path to read sensitive calendar-accessible data and potentially perform unauthorized insert, update, or delete operations.
7. Use any exposed information or changed data to support follow-on fraud, business process manipulation, lateral application access, or further social engineering.

How to detect it

To determine whether exploitation may have occurred, review Oracle HTTP Server, Apache, reverse proxy, WAF, load balancer, and Oracle E-Business Suite application logs for suspicious HTTP requests to calendar-related E-Business Suite paths. Focus on requests that coincide with phishing reports, unusual external referrers, unexpected redirects, encoded parameters, abnormal query strings, or requests initiated immediately after a user clicked an external link. Review authenticated user activity for abnormal calendar data reads, inserts, updates, or deletes, especially actions inconsistent with the user’s role, source IP history, or normal working hours. Correlate web requests with E-Business Suite session records, application audit trails, database audit logs for calendar-related objects, and identity provider logs. Because no public exploit artifact is provided in the input, detection should emphasize behavioral signs: user-driven requests from suspicious referrers, unexpected state-changing requests, anomalous access to calendar data, and unusual post-interaction application activity. Also check WAF and proxy logs for blocked or allowed requests containing heavily encoded parameters, cross-site request patterns, or attempts to invoke Oracle E-Business Suite OA_HTML functionality from external pages.

What your security team should do

• Prioritize patching because the vulnerability is remotely reachable over HTTP, requires no attacker authentication, has high confidentiality impact, and has a high EPSS score.
• Inventory all Oracle E-Business Suite instances, including non-production, disaster-recovery, externally published, and legacy 12.1.x or 12.2.x environments.
• Apply the relevant Oracle Critical Patch Update or later cumulative security patch to affected versions 12.1.1-12.1.3 and 12.2.3-12.2.10.
• Restrict Oracle E-Business Suite access to trusted networks, VPN, or identity-aware proxy paths while patching is in progress.
• Review web access logs for suspicious requests to Oracle E-Business Suite calendar functionality, especially requests with external referrers or unusual parameters around the time users reported suspicious links.
• Harden user interaction paths by enabling phishing-resistant MFA where supported, secure session settings, anti-CSRF protections provided by Oracle patches, and safe-link inspection for links pointing to Oracle E-Business Suite.
• Notify SOC and application support teams to monitor for anomalous calendar data access, unexpected calendar record changes, and unusual Oracle E-Business Suite activity following suspicious user interactions.