CVE-2026-19671

Improper handling of highly compressed data (data amplification) in CISA Malcolm

Published Aug 18, 2026 CVSS 4.0 · 7.1 High EPSS < 1% KEV · Not listed
Description
Malcolm's upload-processing pipeline (scripts/safe-extract.py) enforces entry-count, nesting-depth, and total-uncompressed-byte limits when extracting container archives (zip/tar/rar/7z via libarchive), but those limits are not applied when the uploaded file is a single-stream compressed format (.gz, .bz2, .xz, .lzma, .lz) that isn't a .tar.*-style archive. Any authenticated user permitted to upload PCAP/log files can upload a small, highly compressible file (e.g. a gzip bomb) that decompresses to an effectively unbounded size on disk, exhausting the shared Docker volume used by OpenSearch, Logstash, Arkime, and Zeek, and disrupting the platform for all users.

Remediation

Vendor Solution

Malcolm version 26.08.0 addresses this issue. For more information, see  https://github.com/cisagov/Malcolm/security/advisories/GHSA-f2v6-8cj4-mhr6 .

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Cisagov
Cisagov malcolm
Vendors & Products Cisagov
Cisagov malcolm
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description Malcolm's upload-processing pipeline (scripts/safe-extract.py) enforces entry-count, nesting-depth, and total-uncompressed-byte limits when extracting container archives (zip/tar/rar/7z via libarchive), but those limits are not applied when the uploaded file is a single-stream compressed format (.gz, .bz2, .xz, .lzma, .lz) that isn't a .tar.*-style archive. Any authenticated user permitted to upload PCAP/log files can upload a small, highly compressible file (e.g. a gzip bomb) that decompresses to an effectively unbounded size on disk, exhausting the shared Docker volume used by OpenSearch, Logstash, Arkime, and Zeek, and disrupting the platform for all users.
Title Improper handling of highly compressed data (data amplification) in CISA Malcolm
Weaknesses CWE-409
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 7.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
icscert
Published
Updated
Aug 18, 2026, 7:45 PM
Reserved
Aug 12, 2026, 9:15 PM
Status
Awaiting Analysis
Published
Aug 18, 2026, 8:17 PM
Modified
Sep 8, 2026, 3:28 PM