CVE-2023-25809: rootless `/sys/fs/cgroup` Is Writable When Cgroupns Vulnerability

LOW
Advisory Identifier: GHSA-m8cg-xc2p-r3fc
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CVSS 2.5
CWE-281
Published
Advisory Summary

CVE-2023-25809 is a LOW (CVSS 2.5) `/sys/fs/cgroup` is writable when cgroupns vulnerability (CWE-281: Improper Preservation of Permissions) affecting rootless libraries in the Go ecosystem. The issue involves `/sys/fs/cgroup` is writable when cgroupns isn't unshared in runc. Remediation is available by upgrading affected packages to version 1.1.5.

CVE-2023-25809 at a Glance

CVE Identifier CVE-2023-25809
GHSA Identifier GHSA-m8cg-xc2p-r3fc
Severity LOW
CVSS v3.1 Base Score 2.5
CWE Classification CWE-281: Improper Preservation of Permissions
Affected Product rootless
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 2.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:L).

Attack Vector Local (AV:L)
Attack Complexity High (AC:H)
Privileges Required High (PR:H)
User Interaction None (UI:N)
Scope Changed (S:C)
Confidentiality None (C:N)
Integrity None (I:N)
Availability Low (A:L)

How to Fix CVE-2023-25809

To remediate this vulnerability, upgrade all affected rootless dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/opencontainers/runc fixed: 1.1.5 
Upgrade github.com/opencontainers/runc to 1.1.5
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for github.com/opencontainers/runc

How to Check if You Are Affected

To determine whether your application is affected by CVE-2023-25809, inspect your project dependencies for rootless:

inspect dependencies for github.com/opencontainers/runc

Analyze the terminal output to locate any version of rootless in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.1.5), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-281: Improper Preservation of Permissions, where the product does not preserve permissions or incorrectly preserves permissions when copying, restoring, or sharing objects, which can cause them to have less restrictive permissions than intended. In rootless, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact It was found that rootless runc makes `/sys/fs/cgroup` writable in following conditons: 1. when runc is executed inside the user namespace, and the `config.json` does not specify the cgroup namespace to be unshared (e.g.., `(docker|podman|nerdctl) run --cgroupns=host`, with Rootless Docker/Podman/nerdctl) 2. or, when runc is executed outside the user namespace, and `/sys` is mounted with `rbind, ro` (e.g., `runc spec --rootless`; this condition is very rare) A container may gain the write access to user-owned cgroup hierarchy `/sys/fs/cgroup/user.slice/...` on the host . Other users's cgroup hierarchies are not affected. ### Patches v1.1.5 (planned) ### Workarounds - Condition 1: Unshare the cgroup namespace (`(docker|podman|nerdctl) run --cgroupns=private)`. This is the default behavior of Docker/Podman/nerdctl on cgroup v2 hosts. - Condition 2 (very rare): add `/sys/fs/cgroup` to `maskedPaths`

CVE-2023-25809 Affected rootless Versions

1 component(s)
Fixed Versions:
1.1.5
Product / Package Ecosystem Affected Versions Fixed Version
github.com/opencontainers/runc
golang/github.com/opencontainers/runc
Go
< 1.1.5
1.1.5

References

GitHub Advisory / Wiki ADVISORY
https://github.com/opencontainers/runc/security/advisories/GHSA-m8cg-xc2p-r3fc
NVD — CVE-2023-25809 NVD
https://nvd.nist.gov/vuln/detail/CVE-2023-25809
Security Fix Commit FIX COMMIT
https://github.com/opencontainers/runc/commit/0d62b950e60f6980b54fe3bafd9a9c608dc1df17
rootless Source Repository REPOSITORY
https://github.com/opencontainers/runc

Frequently Asked Questions

What is CVE-2023-25809?
CVE-2023-25809 is a security vulnerability in rootless involving `/sys/fs/cgroup` is writable when cgroupns isn't unshared in runc under CWE-281: Improper Preservation of Permissions.
Which rootless versions are affected?
Affected versions include releases prior to 1.1.5 across affected packages: github.com/opencontainers/runc.
What version fixes CVE-2023-25809?
Upgrading to 1.1.5 (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/opencontainers/runc affected?
Yes, github.com/opencontainers/runc is affected in releases prior to 1.1.5. Upgrade your dependency to 1.1.5 or later.
What is the CVSS score of CVE-2023-25809?
CVE-2023-25809 has a CVSS v3.1 base score of 2.5 (LOW) with vector string CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:L.
What CWE is associated with CVE-2023-25809?
CVE-2023-25809 is classified under CWE-281: Improper Preservation of Permissions (The product does not preserve permissions or incorrectly preserves permissions when copying, restoring, or sharing objects, which can cause them to have less restrictive permissions than intended.).
How can I check Go dependencies for CVE-2023-25809?
Run the dependency tree command: 'inspect dependencies for github.com/opencontainers/runc'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-m8cg-xc2p-r3fc",
  "modified" : "2023-03-30T20:17:24Z",
  "published" : "2023-03-30T20:17:24Z",
  "aliases" : [ "CVE-2023-25809" ],
  "summary" : "rootless: `/sys/fs/cgroup` is writable when cgroupns isn't unshared in runc",
  "details" : "### Impact\nIt was found that rootless runc makes `/sys/fs/cgroup` writable in following conditons:\n1. when runc is executed inside the user namespace, and the `config.json` does not specify the cgroup namespace to be unshared (e.g.., `(docker|podman|nerdctl) run --cgroupns=host`, with Rootless Docker/Podman/nerdctl)\n2. or, when runc is executed outside the user namespace, and `/sys` is mounted with `rbind, ro` (e.g., `runc spec --rootless`; this condition is very rare)\n\nA container may gain the write access to user-owned cgroup hierarchy `/sys/fs/cgroup/user.slice/...` on the host .\nOther users's cgroup hierarchies are not affected.\n\n### Patches\nv1.1.5 (planned)\n\n### Workarounds\n- Condition 1: Unshare the cgroup namespace (`(docker|podman|nerdctl) run --cgroupns=private)`. This is the default behavior of Docker/Podman/nerdctl on cgroup v2 hosts.\n- Condition 2 (very rare): add `/sys/fs/cgroup` to `maskedPaths`\n",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/opencontainers/runc"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.1.5"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/opencontainers/runc/security/advisories/GHSA-m8cg-xc2p-r3fc"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2023-25809"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/opencontainers/runc/commit/0d62b950e60f6980b54fe3bafd9a9c608dc1df17"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/opencontainers/runc"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-281" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-03-30T20:17:24Z",
    "nvd_published_at" : "2023-03-29T19:15:00Z"
  }
}