---
id: CVE-2026-35346
aliases:
  - GHSA-6gcw-w7cp-94g9
title: 'comm: lossy UTF-8 conversion silently corrupts non-UTF-8 output'
summary: 'comm: lossy UTF-8 conversion silently corrupts non-UTF-8 output'
severity: low
cvss: 3.3
cwe:
  - CWE-116
  - CWE-176
vendor: uu_comm
product: uu_comm
ecosystem: rust
affected:
  - uu_comm < 0.6.0
patched:
  - uu_comm 0.6.0
published: '2026-07-06'
updated: '2026-07-06'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-6gcw-w7cp-94g9'
references:
  - url: >-
      https://github.com/uutils/coreutils/security/advisories/GHSA-6gcw-w7cp-94g9
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-35346'
  - url: 'https://github.com/uutils/coreutils/issues/10192'
  - url: 'https://github.com/uutils/coreutils/pull/10206'
  - url: >-
      https://github.com/uutils/coreutils/commit/b9372e509ea9b278fe13763237067a261bb8c946
  - url: 'https://github.com/uutils/coreutils/releases/tag/0.6.0'
  - url: 'https://github.com/advisories/GHSA-6gcw-w7cp-94g9'
tags:
  - ghsa
  - rust
epss: 0.00176
epssPercentile: 0.07381
ingestedAt: '2026-07-06T20:46:12.693Z'
---

## Overview

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`._

## Affected packages

- `uu_comm < 0.6.0`

## Remediation

Upgrade to a patched release:

- `uu_comm 0.6.0`