🔥 Deep Dive: CVE-2025-29891 — Bypass/Injection in Apache Camel’s Incoming Header Filter By CyberDudeBivash

August 08, 2025

🔥 Deep Dive: CVE-2025-29891 — Bypass/Injection in Apache Camel’s Incoming Header Filter By CyberDudeBivash — Cybersecurity & AI Expert

What: A flaw in Apache Camel’s default incoming header filter lets attackers smuggle Camel-specific control headers in via HTTP headers or parameters. These headers can change route behavior and, with certain components (e.g., camel-bean, camel-exec), lead to method hijacking or remote command execution.
Affected: Camel 4.10.0 < 4.10.2, 4.8.0 < 4.8.5, 3.10.0 < 3.22.4.
Exposure: Any Camel app reachable from the Internet through camel-servlet / camel-jetty / camel-undertow / camel-platform-http / camel-netty-http is vulnerable out of the box.
Fix: Upgrade to 4.10.2, 4.8.5, or 3.22.4. Until then, hard-block Camel control headers and use an allowlist for incoming headers/params.

📌 Related: CVE-2025-27636 was initially scoped to malicious HTTP headers only; CVE-2025-29891 confirms the same root cause is also exploitable via HTTP parameters, not just headers.

1) What actually breaks

Camel maps inbound HTTP data to message Headers. The default incoming header filter failed to reject a set of Camel control headers when they arrive as (a) HTTP headers or (b) HTTP parameters (query string/form). If a route includes header-driven components, the attacker can steer execution.

Dangerous examples (not exhaustive)

camel-bean: honors headers like CamelBeanMethodName (select method), CamelBeanMultiParameterArray, etc.
→ Lets attacker invoke arbitrary bean methods exposed to the route.
camel-exec: honors headers like CamelExecCommand, CamelExecArguments, CamelExecWorkingDir.
→ Lets attacker run OS commands under the service account.

Key insight: Nothing “memory-corrupts.” It’s behavioral injection—you let user-controlled data become Camel headers, and some components treat those as instructions.

2) Affected versions & surfaces

Versions:
- 4.10.0 – 4.10.1 (fixed in 4.10.2)
- 4.8.0 – 4.8.4 (fixed in 4.8.5)
- 3.10.0 – 3.22.3 (fixed in 3.22.4)
Ingress components (Internet-facing)
camel-servlet, camel-jetty, camel-undertow, camel-platform-http, camel-netty-http
“Sink” components (high risk if present in route)
camel-bean, camel-exec (and any component that changes behavior based on Camel headers)

Pre-conditions to exploit:

Your Camel app is reachable via HTTP(S).
The route maps inbound HTTP data to Camel message headers (default).
The route later passes those headers to behavior-sensitive components (e.g., bean/exec).

3) Attack paths (how it’s exploited)

3.1 Bean method hijack (no OS commands—still bad)

Route snippet (Java DSL):

java
from("platform-http:/orders")
  .bean(OrderService.class);  // selects method from headers if present

Exploit (as HTTP parameter → becomes header):

bash
curl "https://api.example.com/orders?CamelBeanMethodName=deleteAll"

If OrderService exposes deleteAll, the call may invoke it—state corruption / data loss.

3.2 OS command execution via camel-exec

Route snippet:

java
from("jetty:http://0.0.0.0:8080/run")
  .to("exec://bash");

Exploit (parameter → header):

bash
curl "http://target:8080/run?CamelExecCommand=/bin/bash&CamelExecArguments=-c,cat%20/etc/passwd"

The component reads CamelExec* headers and executes. RCE achieved.

Note: Attackers can also supply the same keys as HTTP headers; 29891 clarifies that parameters work too.

4) Risk & MITRE ATT&CK mapping

T1190 Exploit Public-Facing Application
T1059 Command and Scripting Interpreter (camel-exec path)
T1210 Exploitation of Remote Services
T1105 Exfiltration over Web Services (HTTP)
T1490/T1485 Service/Data Destruction possible via bean method abuse

Impact: RCE, data tampering, arbitrary method calls, credential exposure (if routes touch secrets), lateral movement.

5) Detection ideas (what to hunt)

5.1 WAF / Reverse proxy

Look for query keys / headers beginning with Camel or known control names:

CamelBeanMethodName, CamelBeanMultiParameterArray
CamelExecCommand, CamelExecArguments, CamelExecWorkingDir

Example (NGINX WAF-like pseudo):

nginx
if ($arg_CamelBeanMethodName != "") { return 403; }
if ($arg_CamelExecCommand != "")   { return 403; }
if ($http_camelexeccommand != "")  { return 403; }

5.2 App logs (Jetty/Undertow/Servlet)

4xx/5xx spikes with those keys present
Unexpected bean invocations / exec component activity
Routes suddenly receiving unknown headers in Exchange.getIn().getHeaders()

5.3 Host/EDR (for camel-exec)

Alert if Camel/Jetty/Java process spawns bash, sh, powershell, cmd, curl, nc, etc.

Linux (auditd example):

python
-w /usr/bin/bash -p x -k camel-exec

6) Immediate mitigations (before you can patch)

6.1 Remove/deny dangerous headers at ingress

Apply an allowlist at the very first route step.

Java DSL:

java
from("platform-http:/orders")
  // keep only the headers your app truly needs
  .process(e -> e.getIn().retainHeaders(Set.of(
      "Content-Type", "Accept", "X-Request-Id", "Authorization")))
  // as a belt-and-suspenders: drop all Camel* and Exec* patterns
  .removeHeaders("Camel*")
  .removeHeaders("CamelExec*")
  .to("bean:OrderService");

XML DSL:

xml
<route>
  <from uri="servlet:/orders"/>
  <removeHeaders pattern="Camel*"/>
  <removeHeaders pattern="CamelExec*"/>
  <to uri="bean:orderService"/>
</route>

If you must pass selected values forward, copy specific parameters into new safe headers you define (e.g., X-Order-Action) and validate them strictly.

6.2 Block on reverse proxy/WAF

Deny requests containing suspicious keys in either headers or query/form.
Add rate-limits and geo/ASN controls on admin or exec routes.

6.3 Disable header-driven behaviors

For camel-bean, avoid auto method selection from headers; bind explicit method:
```
java
.bean(OrderService.class, "create")  // fixed method
```
For camel-exec, do not derive command or args from user input.

7) Permanent remediation

Upgrade immediately
- 4.10.x → 4.10.2
- 4.8.x → 4.8.5
- 3.x → 3.22.4
Enable the fixed header filtering in the upgraded version (defaults will be corrected).
Security review of routes:
- Inventory where headers/params influence behavior (bean/exec/custom processors).
- Convert dynamic choices into validated enums / explicit method bindings.
Threat model Internet-facing routes and place them behind authN/Z, WAF, and rate limits.

8) Verification & regression tests

Unit test that requests containing Camel* / CamelExec* in either headers or params are rejected or sanitized.
Integration test: attempt to set CamelBeanMethodName and confirm it does not change invocation.
EDR test: verify no shell child-process spawns from the JVM under normal traffic.

9) Developer secure-coding checklist (Camel)

Never let user input decide bean method names or exec commands.
Apply header allowlists right after the from(...).
Use explicit methods in .bean(Class, "method").
Keep ingress components behind auth & WAF.
Log and block any header/param starting with Camel* unless explicitly required.
Patch Camel to 4.10.2 / 4.8.5 / 3.22.4 and re-deploy.

10) Exec brief (for leadership)

CVE-2025-29891 lets attackers inject Camel control headers via HTTP headers or parameters, steering routes that use components like camel-bean/exec into dangerous behavior (up to RCE). We’ve (1) upgraded Camel, (2) enforced header allowlists & WAF blocks, and (3) audited routes for header-driven logic. Monitoring is in place for any shell spawns and suspicious header patterns.

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