Which versions of Malcolm are affected by CVE-2026-63133?

A high-severity availability flaw in Malcolm, CISA's network traffic analysis suite, allows any authenticated low-privilege user with access to the PCAP upload interface to disable the filebeat…. A patch is available.

How to fix or mitigate CVE-2026-63133?

Within 24 hours, confirm whether Malcolm is deployed in your environment, identify all instances running versions prior to 26.07.0, and restrict access to the archive/PCAP upload path to only the users and service accounts that genuinely require it; review authentication logs for anomalous bulk-upload activity. Within 7 days, upgrade all Malcolm deployments to version 26.07.0, which fixes the missing entry-count, depth, and output-size limits in safe-extract.py, and validate the upgrade in a staging or non-production environment first to confirm the processing pipeline resumes normal operation. Within 30 days, verify that the filebeat processing container and any services sharing the same mount are isolated from unrelated workloads, apply resource quotas or inode limits at the container/filesystem layer as defense in depth, and add the upgrade to your standard vulnerability remediation reporting so completion is tracked to closure.

Malcolm CVE-2026-63133

Q: What is the CVSS score of CVE-2026-63133?

CVE-2026-63133 has a CVSS 4.0 base score of 7.1 (High). 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.2%.

EUVD-2026-56969 HIGH

Allocation of Resources Without Limits or Throttling (CWE-770)

2026-08-11 GitHub_M

Denial Of Service Malcolm Cisagov

7.1

CVSS 4.0 · Vendor: GitHub_M

Severity by source

Vendor (GitHub_M) PRIMARY

7.1 MEDIUM

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

vuln.today AI

6.5 MEDIUM

Network-reachable archive upload with low complexity and no UI, but requires low-privilege upload access (PR:L); impact is availability-only (A:H), with no confidentiality or integrity effect and unchanged scope.

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Lifecycle Timeline

Analysis Updated

Oct 02, 2026 - 21:27 vuln.today

v2 (cvss_changed)

Re-analysis Queued

Oct 02, 2026 - 21:22 vuln.today

cvss_changed

Severity Changed

Oct 02, 2026 - 21:22 NVD

MEDIUM HIGH

CVSS changed

Oct 02, 2026 - 21:22 NVD

6.5 (MEDIUM) 7.1 (HIGH)

Analysis Generated

Aug 11, 2026 - 23:52 vuln.today

Patch available

Aug 11, 2026 - 22:04 EUVD

DescriptionCVE.org

Malcolm is a network traffic analysis tool suite. Prior to version 26.07.0, safe-extract.py extracts uploaded archives with no limit on entry count, directory depth, total entries, or output size. A small malicious archive containing a large number of directory or file entries causes the filebeat processing container to create an unbounded number of filesystem objects, exhausting inodes or filesystem metadata and denying service to the processing pipeline and any service sharing the same mount. Version 26.07.0 fixes the issue.

AnalysisAI

Unbounded archive extraction in Malcolm, CISA's network traffic analysis tool suite, allows a user who can reach the archive/PCAP upload path (authenticated, low-privilege per the CVSS PR:L vector) to exhaust filesystem inodes and metadata on the filebeat processing container by submitting a small malicious archive containing an enormous number of directory or file entries, denying service to the processing pipeline and to any service sharing the same mount. safe-extract.py in all versions before 26.07.0 places no limit on entry count, directory depth, total entries, or output size, so the failure is a pure availability impact with no confidentiality or integrity loss (VC:N/VI:N/VA:H). Version 26.07.0 fixes the issue, the EPSS score is a low 0.25% (16th percentile), the CISA SSVC assessment records proof-of-concept exploitation with Automatable set to no, and there is no CISA KEV listing, making this a genuine but moderate-priority availability defect rather than a critical emergency.

Technical ContextAI

The root cause is CWE-770 (Allocation of Resources Without Limits or Throttling). Malcolm is a Docker-based network traffic analysis suite built around a Filebeat-based ingest and processing pipeline, and its helper script safe-extract.py is responsible for unpacking uploaded archives inside the filebeat processing container. The script performs extraction without constraining the number of archive entries, the directory nesting depth, the total entry count, or the resulting output size, so a deliberately crafted archive that is tiny on disk can expand into an arbitrarily large number of filesystem objects (directories and files) on the container's mounted volume. Because filesystem inodes and metadata are a shared, finite resource, the amplification factor here is not bytes but object count: consuming the inode table denies the creation of any further files on that mount, which is why the impact extends to other services that share the mount. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N) and the independent CVSS 3.1 assessment (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) agree that this is a network-reachable, low-complexity, low-privilege-triggered, high-availability-impact flaw with no privilege escalation, data exposure, or integrity loss; the PR:L component reflects that exploitation requires upload capability on Malcolm's archive ingestion path, and the low Automatable rating in SSVC is consistent with the need for a purpose-built archive rather than a trivial spray. The CPE cpe:2.3:a:cisagov:malcolm:*:*:*:*:*:*:*:* confirms the affected package is Malcolm itself across all releases before the fixed version.

RemediationAI

Vendor-released patch: upgrade Malcolm to version 26.07.0, which adds the missing limits to safe-extract.py; the fixed artifacts are published at https://github.com/cisagov/Malcolm/releases/tag/v26.07.0 and the fix is described in GHSA-c35g-mgc3-95rx (https://github.com/cisagov/Malcolm/security/advisories/GHSA-c35g-mgc3-95rx) and CISA ICS advisory ICSA-26-230-01 (https://www.cisa.gov/news-events/ics-advisories/icsa-26-230-01). Where immediate upgrade is not possible, apply compensating controls targeted at the upload path and the shared filesystem: restrict access to Malcolm's archive/PCAP upload endpoint to trusted operators only, since the CVSS PR:L vector means the attack requires upload privileges and removing those privileges removes the vector (trade-off: breaks normal multi-user ingestion workflows); enforce a maximum upload size and archive entry count at an upstream proxy or upload gateway so oversized or entry-dense archives are rejected before reaching the container (trade-off: legitimate large or deeply nested captures may be blocked and must be submitted in smaller batches); and, most directly, move the filebeat container's extraction directory onto a dedicated filesystem or volume with a hard inode and space quota so that inode exhaustion is contained to the processing container and does not deny services sharing the same mount (trade-off: legitimate bursts of extraction may fail earlier once the quota is reached, and quota limits must be tuned to normal ingestion volume). Additionally monitor inode consumption on the shared mount with alerting so an ongoing exhaustion attempt is visible before the pipeline stalls, and, if a compromise is suspected, free the offending filesystem objects or recreate the affected volume to restore service.