CVE-2026-35346: comm Lossy UTF-8 Conversion Silently Corrupts Vulnerability

LOW
Advisory Identifier: GHSA-6gcw-w7cp-94g9
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CVSS 3.3
CWE-116 CWE-176
Published
Advisory Summary

CVE-2026-35346 is a LOW (CVSS 3.3) lossy utf-8 conversion silently corrupts vulnerability (CWE-116: Improper Encoding or Escaping of Output) affecting comm libraries in the crates.io ecosystem. The issue involves lossy utf-8 conversion silently corrupts non-utf-8 output. Remediation is available by upgrading affected packages to version 0.6.0.

CVE-2026-35346 at a Glance

CVE Identifier CVE-2026-35346
GHSA Identifier GHSA-6gcw-w7cp-94g9
Severity LOW
CVSS v3.1 Base Score 3.3
CWE Classification CWE-116: Improper Encoding or Escaping of Output
Affected Product comm
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 3.3

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:N).

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 None (A:N)

How to Fix CVE-2026-35346

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-2026-35346, 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-116: Improper Encoding or Escaping of Output, where the product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. as a result, the intended structure of the message is not preserved. 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 silently corrupts data by performing lossy UTF-8 conversion on all output lines. The implementation uses String::from_utf8_lossy(), which replaces invalid UTF-8 byte sequences with the Unicode replacement character (U+FFFD). This behavior differs from GNU comm, which processes raw bytes and preserves the original input. This results in corrupted output when the utility is used to compare binary files or files using non-UTF-8 legacy encodings. --- _Zellic finding 3.34. Reported in the Zellic *uutils coreutils Program Security Assessment* (for Canonical, Jan 2026), audited commit `3a07ffc5a9bd4c283e75afa548ba1f1957bad242`._

CVE-2026-35346 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-6gcw-w7cp-94g9
NVD — CVE-2026-35346 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-35346
comm Source Repository REPOSITORY
https://github.com/uutils/coreutils/issues/10192
comm Source Repository REPOSITORY
https://github.com/uutils/coreutils/pull/10206
Security Fix Commit FIX COMMIT
https://github.com/uutils/coreutils/commit/b9372e509ea9b278fe13763237067a261bb8c946
comm Source Repository REPOSITORY
https://github.com/uutils/coreutils
comm Release RELEASE
https://github.com/uutils/coreutils/releases/tag/0.6.0

Frequently Asked Questions

What is CVE-2026-35346?
CVE-2026-35346 is a security vulnerability in comm involving lossy UTF-8 conversion silently corrupts non-UTF-8 output under CWE-116: Improper Encoding or Escaping of Output.
Which comm versions are affected?
Affected versions include releases prior to 0.6.0 across affected packages: uu_comm.
What version fixes CVE-2026-35346?
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-2026-35346?
CVE-2026-35346 has a CVSS v3.1 base score of 3.3 (LOW) with vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N.
What CWE is associated with CVE-2026-35346?
CVE-2026-35346 is classified under CWE-116: Improper Encoding or Escaping of Output (The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.).
How can I check crates.io dependencies for CVE-2026-35346?
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-6gcw-w7cp-94g9",
  "modified" : "2026-07-06T19:51:22Z",
  "published" : "2026-07-06T19:51:22Z",
  "aliases" : [ "CVE-2026-35346" ],
  "summary" : "comm: lossy UTF-8 conversion silently corrupts non-UTF-8 output",
  "details" : "The comm utility in uutils coreutils silently corrupts data by performing lossy UTF-8 conversion on all output lines. The implementation uses String::from_utf8_lossy(), which replaces invalid UTF-8 byte sequences with the Unicode replacement character (U+FFFD). This behavior differs from GNU comm, which processes raw bytes and preserves the original input. This results in corrupted output when the utility is used to compare binary files or files using non-UTF-8 legacy encodings.\n\n---\n_Zellic finding 3.34. 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:N"
  } ],
  "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-6gcw-w7cp-94g9"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-35346"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/uutils/coreutils/issues/10192"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/uutils/coreutils/pull/10206"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/uutils/coreutils/commit/b9372e509ea9b278fe13763237067a261bb8c946"
  }, {
    "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-116", "CWE-176" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-06T19:51:22Z",
    "nvd_published_at" : null
  }
}