# 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.

- **Severity:** High 7.1 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 18 Aug 2026
- **Updated:** 18 Aug 2026
- **Also known as:** GHSA-3wrw-4pcx-6p2g

## 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 (Improper Handling of Highly Compressed Data (Data Amplification))

## 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.

## Is CVE-2026-19671 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-19671 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-19671 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-19671 exists.

Affected product: CISAgov Malcolm. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-19671/ (Markdown: https://insights.sbomify.com/CVE-2026-19671/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-19671
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-19671
- OSV: https://osv.dev/vulnerability/CVE-2026-19671

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-19671/
Summaries are generated and may contain mistakes; the official description above is the record.