CVE-2026-41179

The RC endpoint operations/fsinfo is exposed without AuthRequired: true and accepts attacker-controlled fs input. Because rc.GetFs(...) supports inline backend definitions, an unauthenticated attacker can instantiate an attacker-controlled backend on demand. For the WebDAV backend, bearer_token_command is executed during backend initialization, making single-request unauthenticated local command execution possible on reachable RC deployments without global HTTP authentication.

Preconditions

Preconditions for this vulnerability are:

• The rclone remote control API must be enabled, either by the --rc flag or by running the rclone rcd server
• The remote control API must be reachable by the attacker - by default rclone only serves the rc to localhost unless the --rc-addr flag is in use
• The rc must have been deployed without global RC HTTP authentication - so not using --rc-user/--rc-pass/--rc-htpasswd/etc

Details

The root cause consists of the following pieces:

1. operations/fsinfo is not protected with AuthRequired: true
2. operations/fsinfo calls rc.GetFs(...) on attacker-controlled input
3. rc.GetFs(...) supports inline backend creation through object-valued fs
4. WebDAV backend initialization executes bearer_token_command

Relevant code paths:

• fs/operations/rc.go

  • operations/fsinfo is registered without AuthRequired: true
  • rcFsInfo() calls rc.GetFs(ctx, in)

• fs/rc/cache.go

  • GetFs() / GetFsNamed() can parse an object-valued fs
  • getConfigMap() converts attacker-controlled JSON into a backend config string

• backend/webdav/webdav.go

  • bearer_token_command is a supported backend option
  • NewFs(...) calls fetchAndSetBearerToken() when bearer_token_command is set
  • fetchBearerToken() invokes exec.Command(...)

This creates a practical single-request unauthenticated command-execution primitive on reachable RC servers without global HTTP authentication.

This was alidated on:

• current master as of 2026-04-14: bf55d5e6d37fd86164a87782191f9e1ffcaafa82
• latest public release tested locally: v1.73.4

This was also validated on a public amd64 Ubuntu host controlled by the tester, using direct host execution (not containerized PoC execution).

PoC

Minimal single-request form PoC

Start a vulnerable RC server:

rclone rcd --rc-addr 127.0.0.1:5572

No --rc-user, no --rc-pass, no --rc-htpasswd.

Then send a single request:

curl -sS -X POST http://127.0.0.1:5572/operations/fsinfo \
  --data-urlencode "fs=:webdav,url='http://127.0.0.1/',vendor=other,bearer_token_command='/usr/bin/touch /tmp/rclone_fsinfo_rce_poc_marker':"

Expected result:

• HTTP 200 JSON response from operations/fsinfo
• /tmp/rclone_fsinfo_rce_poc_marker is created on the host

Testing performed

This was successfully reproduced:

• on a local test environment
• on a public amd64 Ubuntu host controlled by the tester

On the public host it was confirmed:

• the unauthenticated operations/fsinfo exploit worked
• command execution occurred on the host
• the issue was reproducible through direct host execution

This is effectively a single-request unauthenticated command-execution vulnerability on reachable RC deployments without global HTTP authentication.

In practice, command execution in the rclone process context can lead to higher-impact outcomes such as local file read, file write, or shell access, depending on the deployed environment.

Untrusted input reaches a shell command, allowing arbitrary commands to run on the host. Typical impact: code execution in the application's environment.

CVE-2026-41179 has a CVSS score of 9.8 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.73.5); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-41179? CVE-2026-41179 is a critical-severity OS command injection vulnerability in github.com/rclone/rclone (go), affecting versions >= 1.48.0, <= 1.73.4. It is fixed in 1.73.5. Untrusted input reaches a shell command, allowing arbitrary commands to run on the host.
2. How severe is CVE-2026-41179? CVE-2026-41179 has a CVSS score of 9.8 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/rclone/rclone are affected by CVE-2026-41179? github.com/rclone/rclone (go) versions >= 1.48.0, <= 1.73.4 is affected.
4. Is there a fix for CVE-2026-41179? Yes. CVE-2026-41179 is fixed in 1.73.5. Upgrade to this version or later.
5. Is CVE-2026-41179 exploitable, and should I be worried? Whether CVE-2026-41179 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-41179 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-41179? Upgrade github.com/rclone/rclone to 1.73.5 or later.