CVE-2026-19671 Improper handling of highly compressed data (data amplification) in CISA Malcolm
Authenticated users can upload compressed files to exhaust disk space, causing denial of service for the entire Malcolm network security platform.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-19671?
CVE-2026-19671 is a high-severity denial of service vulnerability in CISAgov Malcolm, published on 18 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-409
Which versions are affected by CVE-2026-19671?
How do I fix CVE-2026-19671?
No fix has been published for CVE-2026-19671 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-19671 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-19671 exists.
Sources
Also known as GHSA-3wrw-4pcx-6p2g.