CVE-2026-52780 Overview
CVE-2026-52780 is a cache store poisoning vulnerability in OpenProject, an open-source web-based project management platform. The flaw enables Remote Code Execution (RCE) through manipulation of the application's cache store. The vulnerability affects OpenProject versions prior to 17.3.3 and 17.4.1.
The issue is categorized under [CWE-20] Improper Input Validation. Successful exploitation allows adversaries on an adjacent network to achieve full compromise of confidentiality, integrity, and availability with a scope change.
Critical Impact
Attackers can poison the OpenProject cache to trigger Remote Code Execution, leading to complete host takeover and lateral movement into project data.
Affected Products
- OpenProject versions prior to 17.3.3
- OpenProject versions prior to 17.4.1 (17.4.x branch)
- Self-hosted OpenProject deployments exposing the affected cache backend
Discovery Timeline
- 2026-06-26 - CVE-2026-52780 published to NVD
- 2026-06-27 - Last updated in NVD database
Technical Details for CVE-2026-52780
Vulnerability Analysis
OpenProject relies on a cache store to serve reusable data across requests and background workers. The vulnerability allows an attacker to inject controlled entries into that cache store because input flowing into cache keys or values is not properly validated.
When the poisoned entries are later deserialized or evaluated by the application, they trigger execution of attacker-supplied logic. The result is Remote Code Execution in the context of the OpenProject application process. The scope-changed impact indicates that compromise extends beyond the vulnerable component to the surrounding runtime.
The adjacent-network attack vector requires the attacker to reach the cache-facing surface, typically the internal service network where OpenProject or its cache backend is exposed. No authentication or user interaction is required.
Root Cause
The root cause is Improper Input Validation [CWE-20] in the code paths that write to and read from the cache store. Untrusted data is stored and then trusted on retrieval, enabling poisoned entries to influence application control flow. The maintainers addressed the flaw in OpenProject 17.3.3 and 17.4.1.
Attack Vector
An adjacent-network attacker sends crafted requests or traffic that reach the cache store used by OpenProject. The attacker inserts a malicious payload keyed to data the application later retrieves and processes. When OpenProject consumes the poisoned entry, it executes attacker-controlled code. Refer to the GitHub Security Advisory for technical specifics.
Detection Methods for CVE-2026-52780
Indicators of Compromise
- Unexpected child processes spawned by the OpenProject Ruby application or its worker processes.
- Anomalous entries in the cache backend (for example Memcached or Redis) containing serialized objects, shell metacharacters, or unusually large payloads.
- Outbound network connections from the OpenProject host to unknown destinations following cache write activity.
- New or modified files under OpenProject application directories not tied to deployments.
Detection Strategies
- Monitor the OpenProject application version and alert on any instance running below 17.3.3 or 17.4.1.
- Inspect cache backend traffic for writes originating from hosts other than the OpenProject application servers.
- Correlate HTTP request logs with subsequent process execution events on OpenProject hosts to identify request-to-RCE chains.
Monitoring Recommendations
- Enable process-execution telemetry on all OpenProject hosts and forward it to a central analytics platform.
- Log all connections to the Redis or Memcached instance backing OpenProject and review access-control lists regularly.
- Track OpenProject version metadata in the asset inventory to accelerate future advisory response.
How to Mitigate CVE-2026-52780
Immediate Actions Required
- Upgrade OpenProject to 17.3.3 or 17.4.1 without delay.
- Restrict network access to the cache backend so that only OpenProject application nodes can reach it.
- Review OpenProject and cache backend logs for signs of exploitation prior to patching.
- Rotate any secrets, API tokens, or credentials accessible from the OpenProject host if compromise is suspected.
Patch Information
The OpenProject maintainers fixed CVE-2026-52780 in versions 17.3.3 and 17.4.1. Details are published in the OpenProject GitHub Security Advisory GHSA-qj96-f42f-6336. Administrators should apply the upgrade using the official OpenProject packages or container images.
Workarounds
- Place the OpenProject cache backend on an isolated network segment reachable only by trusted application nodes.
- Enable authentication and require TLS on Redis or Memcached instances used by OpenProject.
- Restrict OpenProject exposure with a reverse proxy that filters malformed requests until the patched version is deployed.
# Configuration example: restrict Redis to the OpenProject application subnet
# /etc/redis/redis.conf
bind 10.20.30.10
protected-mode yes
requirepass <strong-random-secret>
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
