comm: FIFO/pipe inputs are drained before comparison (data loss / hang)

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

4.4 · CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L

EPSS

• CVE-2026-35347: 0.14% estimated exploitation activity in the next 30 days; percentile 2.96 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

The comm utility in uutils coreutils incorrectly consumes data from non-regular file inputs before performing comparison operations. The arefilesidentical 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.

Published by the source

6 Jul 2026, 20:17 UTC

Last modified by the source

6 Jul 2026, 20:18 UTC

Source last checked

26 Oct 2026, 15:43 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-3wfc-mgpm-9rq6

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# Patch Next advisory brief: CVE-2026-35347

Advisory: comm: FIFO/pipe inputs are drained before comparison (data loss / hang)
IDs: CVE-2026-35347, GHSA-3wfc-mgpm-9rq6
Record: https://patchnext.com/advisories/cve-2026-35347 (revision 1, source checked 26 Oct 2026, 15:43 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: uu_comm 0.6.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io uu_comm: affected < 0.6.0; fixed in 0.6.0

## Suggested inspection (read-only)
- crates.io uu_comm: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on uu_comm.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-3wfc-mgpm-9rq6 (GitHub-reviewed advisory GHSA-3wfc-mgpm-9rq6 lists affected ranges: crates.io uu_comm >=0 <0.6.0)

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