Summary
CVE-2025-27636 is a remote code execution vulnerability in Apache Camel. It happens because certain HTTP headers in the exec component are only checked in lowercase, letting attackers bypass the filter by changing the header case. Exploiting this flaw can make Camel run system commands with the process’s privileges.
Urgent Actions Required
- Upgrade Apache Camel to 4.10.2, 4.8.5, or 3.22.4
- Restrict external access to management endpoints like the Command Center
- Filter or sanitize incoming HTTP headers that could influence command execution
- Use a WAF to detect unusual or suspicious header patterns
- Run Apache Camel with a non-privileged account to reduce impact if exploited
Which Systems Are Vulnerable to CVE-2025-27636?
Technical Overview
- Vulnerability Type: Improper header filtering leading to header injection and possible behavior manipulation in multiple Apache Camel components.
- Affected Software/Versions:
- Apache Camel 3.10.0 – 3.22.3
- Apache Camel 4.8.0 – 4.8.4
- Apache Camel 4.10.0 – 4.10.1
- Red Hat builds using affected Camel HTTP components (camel-http / camel-http-base)
- Attack Vector: Network (HTTP)
- CVSS Score: 5.6
- CVSS Vector: v3.1
- Attack Vector: Network
- Attack Complexity: High
- Privileges Required: None
- User Interaction: None
- Scope: Unchanged
- Confidentiality Impact: Low
- Integrity Impact: Low
- Availability Impact: Low
- Patch Availability: Yes, available
How Does the CVE-2025-27636 Exploit Work?
The attack typically follows these steps:
What Causes CVE-2025-27636?
Vulnerability Root Cause:
The issue originates from a flaw in Camel’s default incoming header filter. The filter is designed to block headers beginning with “Camel”, “camel”, or “org.apache.camel.”, but it does not account for variations created through mixed or altered casing. Because of this, attackers can introduce crafted headers that bypass the filter. These injected headers may influence the behavior of several Camel components, including enabling unintended method calls in the bean component or redirecting messages in messaging components. The weakness is directly tied to inconsistent handling of case sensitivity when assessing header names.
How Can You Mitigate CVE-2025-27636?
If immediate patching is delayed or not possible:
- Remove incoming headers in Camel routes to prevent crafted header injection.
- Use the removeHeaders EIP to clear header variations such as mixed-case forms that bypass the default filter.
- Apply header removal either globally or per specific route to block any header that does not begin with the expected Camel prefixes.
- Ensure Camel applications exposed directly over HTTP sanitize all external headers before being processed by vulnerable components.
Will Patching CVE-2025-27636 Cause Downtime?
Patch application impact: Upgrading to Camel 3.22.4, 4.8.5, or 4.10.2 will take minimal downtime.
How Can You Detect CVE-2025-27636 Exploitation?
Indicators of Compromise (IOCs/IOAs):
- Processing of XML payloads with external entity definitions inside routes using the affected Apache Camel versions.
Behavioral Indicators:
- Camel routes receiving XML with entity expansion may return or log unexpected data exposure due to the external entity resolution.
Alerting Strategy:
- Trigger alerts for:
Incoming or internal XML documents containing external entity declarations when handled by the vulnerable Camel data format.
Remediation & Response
Mitigation Steps if No Patch:
- Avoid processing untrusted XML input through the affected Camel data formats until patched.
- Add checks to reject XML that includes external entity declarations (e.g., ).
- Limit data processing to sources that are already validated to prevent unexpected entity expansion.
Remediation Timeline:
- Immediate: Reduce or halt handling of XML from untrusted origins in routes using the vulnerable data formats.
- When available for your release line: Update to the patched Apache Camel versions (3.22.4, 4.8.5, 4.10.2) to remove the XXE flaw.
- After patching: Verify the updated components are now enforcing safe XML handling.
Rollback Plan:
If the patched Camel update causes operational issues in XML-processing routes, revert to the previously stable version and continue blocking XML containing external entities until the patch can be safely applied again.
Incident Response Considerations:
- Review logs for routes that processed XML to identify whether external entity resolution occurred unexpectedly.
- Check for responses or data flows that contain information not intended to be returned, indicating possible data exposure from entity expansion.
- If suspicious activity is found, isolate affected routes and restrict further XML processing until patched.
Where Can I Find More Information on CVE-2025-43300?
CVSS Breakdown Table
| Metric | Value | Description |
|---|---|---|
| Base Score | 5.6 | Medium-severity issue |
| Attack Vector | Network | The flaw can be triggered remotely over a network |
| Attack Complexity | High | Exploitation requires specific conditions or crafted inputs |
| Privileges Required | None | No authentication or prior access is needed |
| User Interaction | None | The issue can be exploited without user action |
| Scope | UnChanged | Impact is limited to the vulnerable component |
| Confidentiality Impact | Low | Limited data exposure is possible |
| Integrity Impact | Low | Minimal impact on data integrity |
| Availability Impact | Low | Only minor disruption to availability |
