CVE-2026-35347: comm FIFO/pipe Inputs Are Drained Before Vulnerability

MODERATE
Advisory Identifier: GHSA-3wfc-mgpm-9rq6
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CVSS 4.4
CWE-20
Published
Advisory Summary

CVE-2026-35347 is a MODERATE (CVSS 4.4) fifo/pipe inputs are drained before vulnerability (CWE-20: Improper Input Validation) affecting comm libraries in the crates.io ecosystem. The issue involves fifo/pipe inputs are drained before comparison (data loss / hang). Remediation is available by upgrading affected packages to version 0.6.0.

CVE-2026-35347 at a Glance

CVE Identifier CVE-2026-35347
GHSA Identifier GHSA-3wfc-mgpm-9rq6
Severity MODERATE
CVSS v3.1 Base Score 4.4
CWE Classification CWE-20: Improper Input Validation
Affected Product comm
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 4.4

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:N/I:L/A:L).

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 None (C:N)
Integrity Low (I:L)
Availability Low (A:L)

How to Fix CVE-2026-35347

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

uu_comm fixed: 0.6.0 
Upgrade uu_comm to 0.6.0
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 uu_comm

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-35347, inspect your project dependencies for comm:

inspect dependencies for uu_comm

Analyze the terminal output to locate any version of comm in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.6.0), 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-20: Improper Input Validation, where the product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. In comm, 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

The comm utility in uutils coreutils incorrectly consumes data from non-regular file inputs before performing comparison operations. The are_files_identical function opens and reads from both input paths to compare content without first verifying if the paths refer to regular files. If an input path is a FIFO or a pipe, this pre-read operation drains the stream, leading to silent data loss before the actual comparison logic is executed. Additionally, the utility may hang indefinitely if it attempts to pre-read from infinite streams like /dev/zero. --- _Zellic finding 3.35. Reported in the Zellic *uutils coreutils Program Security Assessment* (for Canonical, Jan 2026), audited commit `3a07ffc5a9bd4c283e75afa548ba1f1957bad242`._

CVE-2026-35347 Affected comm Versions

1 component(s)
Fixed Versions:
0.6.0
Product / Package Ecosystem Affected Versions Fixed Version
uu_comm
 crates.io
< 0.6.0
0.6.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/uutils/coreutils/security/advisories/GHSA-3wfc-mgpm-9rq6
NVD — CVE-2026-35347 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-35347
comm Source Repository REPOSITORY
https://github.com/uutils/coreutils/pull/9545
comm Source Repository REPOSITORY
https://github.com/uutils/coreutils
Security Fix Commit FIX COMMIT
https://github.com/uutils/coreutils/commit/75f45e87e52ed95840494963ab9a28651165d56e
comm Release RELEASE
https://github.com/uutils/coreutils/releases/tag/0.6.0

Frequently Asked Questions

What is CVE-2026-35347?
CVE-2026-35347 is a security vulnerability in comm involving FIFO/pipe inputs are drained before comparison (data loss / hang) under CWE-20: Improper Input Validation.
Which comm versions are affected?
Affected versions include releases prior to 0.6.0 across affected packages: uu_comm.
What version fixes CVE-2026-35347?
Upgrading to 0.6.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is uu_comm affected?
Yes, uu_comm is affected in releases prior to 0.6.0. Upgrade your dependency to 0.6.0 or later.
What is the CVSS score of CVE-2026-35347?
CVE-2026-35347 has a CVSS v3.1 base score of 4.4 (MODERATE) with vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L.
What CWE is associated with CVE-2026-35347?
CVE-2026-35347 is classified under CWE-20: Improper Input Validation (The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.).
How can I check crates.io dependencies for CVE-2026-35347?
Run the dependency tree command: 'inspect dependencies for uu_comm'. 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-3wfc-mgpm-9rq6",
  "modified" : "2026-07-06T20:17:59Z",
  "published" : "2026-07-06T20:17:59Z",
  "aliases" : [ "CVE-2026-35347" ],
  "summary" : "comm: FIFO/pipe inputs are drained before comparison (data loss / hang)",
  "details" : "The comm utility in uutils coreutils incorrectly consumes data from non-regular file inputs before performing comparison operations. The are_files_identical function opens and reads from both input paths to compare content without first verifying if the paths refer to regular files. If an input path is a FIFO or a pipe, this pre-read operation drains the stream, leading to silent data loss before the actual comparison logic is executed. Additionally, the utility may hang indefinitely if it attempts to pre-read from infinite streams like /dev/zero.\n\n---\n_Zellic finding 3.35. Reported in the Zellic *uutils coreutils Program Security Assessment* (for Canonical, Jan 2026), audited commit `3a07ffc5a9bd4c283e75afa548ba1f1957bad242`._",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "uu_comm"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.6.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/uutils/coreutils/security/advisories/GHSA-3wfc-mgpm-9rq6"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-35347"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/uutils/coreutils/pull/9545"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/uutils/coreutils/commit/75f45e87e52ed95840494963ab9a28651165d56e"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/uutils/coreutils"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/uutils/coreutils/releases/tag/0.6.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-20" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-06T20:17:59Z",
    "nvd_published_at" : null
  }
}