CVE-2025-27591: Below Remote Code Execution Vulnerability

HIGH
Advisory Identifier: GHSA-9mc5-7qhg-fp3w
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CVSS 7.8
CWE-732
Published
Advisory Summary

CVE-2025-27591 is a HIGH (CVSS 7.8) remote code execution vulnerability (CWE-732: Incorrect Permission Assignment for Critical Resource) affecting Below libraries in the crates.io ecosystem. The issue involves below has incorrect permission assignment for critical resource. Remediation is available by upgrading affected packages to version 0.9.0.

CVE-2025-27591 at a Glance

CVE Identifier CVE-2025-27591
GHSA Identifier GHSA-9mc5-7qhg-fp3w
Severity HIGH
CVSS v3.1 Base Score 7.8
CWE Classification CWE-732: Incorrect Permission Assignment for Critical Resource
Affected Product Below
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 7.8

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

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

How to Fix CVE-2025-27591

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

below fixed: 0.9.0 
Upgrade below to 0.9.0
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 below

How to Check if You Are Affected

To determine whether your application is affected by CVE-2025-27591, inspect your project dependencies for Below:

inspect dependencies for below

Analyze the terminal output to locate any version of Below in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.9.0), 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-732: Incorrect Permission Assignment for Critical Resource, where the product specifies permissions for a security-critical resource in a way that allows that resource to be read or modified by unintended actors. In Below, 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 A privilege escalation vulnerability existed in the Below service prior to v0.9.0 due to the creation of a world-writable directory at /var/log/below. This could have allowed local unprivileged users to escalate to root privileges through symlink attacks that manipulate files such as /etc/shadow. ### Patches https://github.com/facebookincubator/below/commit/10e73a21d67baa2cd613ee92ce999cda145e1a83 This is included in version 0.9.0 ### Workarounds Change the permission on `/var/log/below` manually ### References https://www.facebook.com/security/advisories/cve-2025-27591 https://www.cve.org/CVERecord?id=CVE-2025-27591

CVE-2025-27591 Affected Below Versions

1 component(s)
Fixed Versions:
0.9.0
Product / Package Ecosystem Affected Versions Fixed Version
below
 crates.io
< 0.9.0
0.9.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/facebookincubator/below/security/advisories/GHSA-9mc5-7qhg-fp3w
NVD — CVE-2025-27591 NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-27591
Security Fix Commit FIX COMMIT
https://github.com/facebookincubator/below/commit/10e73a21d67baa2cd613ee92ce999cda145e1a83
Security Fix Commit FIX COMMIT
https://github.com/facebookincubator/below/commit/da9382e6e3e332fd2c3195e22f34977f83f0f1f3
Below Source Repository REPOSITORY
https://github.com/facebookincubator/below
rustsec.org/advisories/rustsec-... WEB
https://rustsec.org/advisories/RUSTSEC-2025-0149.html
Below Security Information SECURITY
https://www.facebook.com/security/advisories/cve-2025-27591
Below Security Information SECURITY
https://www.openwall.com/lists/oss-security/2025/03/12/1
Below Security Information SECURITY
http://www.openwall.com/lists/oss-security/2025/03/12/1

Frequently Asked Questions

What is CVE-2025-27591?
CVE-2025-27591 is a security vulnerability in Below involving Below has Incorrect Permission Assignment for Critical Resource under CWE-732: Incorrect Permission Assignment for Critical Resource.
Which Below versions are affected?
Affected versions include releases prior to 0.9.0 across affected packages: below.
What version fixes CVE-2025-27591?
Upgrading to 0.9.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is below affected?
Yes, below is affected in releases prior to 0.9.0. Upgrade your dependency to 0.9.0 or later.
What is the CVSS score of CVE-2025-27591?
CVE-2025-27591 has a CVSS v3.1 base score of 7.8 (HIGH) with vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2025-27591?
CVE-2025-27591 is classified under CWE-732: Incorrect Permission Assignment for Critical Resource (The product specifies permissions for a security-critical resource in a way that allows that resource to be read or modified by unintended actors.).
How can I check crates.io dependencies for CVE-2025-27591?
Run the dependency tree command: 'inspect dependencies for below'. 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-9mc5-7qhg-fp3w",
  "modified" : "2026-02-08T01:00:10Z",
  "published" : "2025-03-11T21:12:54Z",
  "aliases" : [ "CVE-2025-27591" ],
  "summary" : "Below has Incorrect Permission Assignment for Critical Resource",
  "details" : "### Impact\nA privilege escalation vulnerability existed in the Below service prior to v0.9.0 due to the creation of a world-writable directory at /var/log/below. This could have allowed local unprivileged users to escalate to root privileges through symlink attacks that manipulate files such as /etc/shadow.\n\n### Patches\nhttps://github.com/facebookincubator/below/commit/10e73a21d67baa2cd613ee92ce999cda145e1a83\n\nThis is included in version 0.9.0\n\n### Workarounds\nChange the permission on `/var/log/below` manually\n\n### References\nhttps://www.facebook.com/security/advisories/cve-2025-27591\nhttps://www.cve.org/CVERecord?id=CVE-2025-27591",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "below"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.9.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/facebookincubator/below/security/advisories/GHSA-9mc5-7qhg-fp3w"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-27591"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/facebookincubator/below/commit/10e73a21d67baa2cd613ee92ce999cda145e1a83"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/facebookincubator/below/commit/da9382e6e3e332fd2c3195e22f34977f83f0f1f3"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/facebookincubator/below"
  }, {
    "type" : "WEB",
    "url" : "https://rustsec.org/advisories/RUSTSEC-2025-0149.html"
  }, {
    "type" : "WEB",
    "url" : "https://www.facebook.com/security/advisories/cve-2025-27591"
  }, {
    "type" : "WEB",
    "url" : "https://www.openwall.com/lists/oss-security/2025/03/12/1"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2025/03/12/1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-732" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-03-11T21:12:54Z",
    "nvd_published_at" : "2025-03-11T19:15:43Z"
  }
}