CVE-2026-19671 PUBLISHED

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

Assigner: icscert
Reserved: 12.08.2026 Published: 18.08.2026 Updated: 18.08.2026

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.

Metrics

CVSS 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
CVSS Score: 7.1

Product Status

Vendor CISAgov
Product Malcolm
Versions Default: unaffected
  • affected from 0 to 26.07.1 (incl.)

Solutions

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

Credits

  • tinyb0y finder

References

Problem Types

  • CWE-409 Improper handling of highly compressed data (data amplification) CWE