CISA Malcolm
All CISA Advisories, CISA, August 18, 2026
Summary
Successful exploitation of these vulnerabilities could allow an attacker to cause a denial-of-service condition or execute arbitrary code.
The following versions of CISA Malcolm are affected:
- Malcolm <26.06.1 (CVE-2026-55676)
- Malcolm <26.07.0 (CVE-2026-63133, CVE-2026-63134, CVE-2026-63177)
- Malcolm <=26.07.1 (CVE-2026-19670, CVE-2026-19671)
| CVSS | Vendor | Equipment | Vulnerabilities |
|---|---|---|---|
| v3 8.8 | CISA | CISA Malcolm | Allocation of Resources Without Limits or Throttling, Improper Limitation of a Pathname to a Restricted Directory (‘Path Traversal’), Unrestricted Upload of File with Dangerous Type, Incorrect Authorization, Improper Handling of Highly Compressed Data (Data Amplification) |
Background
- Critical Infrastructure Sectors: Information Technology
- Countries/Areas Deployed: Worldwide
- Company Headquarters Location: United States
Vulnerabilities
CVE-2026-63133
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.
Affected Products
CISA Malcolm
CISA
CISA Malcolm: <26.07.0
known_affected
Remediations
Vendor fix
Malcolm version 26.07.0 addresses these issues. For more information, see https://github.com/cisagov/Malcolm/pull/1043. (CVE-2026-63133, CVE-2026-63134, CVE-2026-63177)
https://github.com/cisagov/Malcolm/pull/1043
Relevant CWE: CWE-770 Allocation of Resources Without Limits or Throttling
Metrics
| CVSS Version | Base Score | Base Severity | Vector String |
|---|---|---|---|
| 3.1 | 6.5 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
| 4.0 | 7.1 | HIGH | 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 |
CVE-2026-63134
Malcolm is a network traffic analysis tool suite. Prior to version 26.07.0, safe-extract.py protects file extraction with libarchive’s secure flags, but creates directory entries with a raw os.makedirs(os.path.join(dest, entry.pathname)) that has no traversal protection. An uploaded malicious archive containing a directory entry with a ../ sequence or an absolute path causes the filebeat processing container to create directories outside the intended extraction directory. Version 26.07.0 fixes the issue.
Affected Products
CISA Malcolm
CISA
CISA Malcolm: <26.07.0
known_affected
Remediations
Vendor fix
Malcolm version 26.07.0 addresses these issues. For more information, see https://github.com/cisagov/Malcolm/pull/1043. (CVE-2026-63133, CVE-2026-63134, CVE-2026-63177)
https://github.com/cisagov/Malcolm/pull/1043
Relevant CWE: CWE-22 Improper Limitation of a Pathname to a Restricted Directory (‘Path Traversal’)
Metrics
| CVSS Version | Base Score | Base Severity | Vector String |
|---|---|---|---|
| 3.1 | 5.4 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L |
| 4.0 | 5.3 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N |
CVE-2026-55676
Malcolm is a network traffic analysis tool suite. The file-upload component (FilePond PHP backend) accepts uploads at POST /server/php/submit.php and stores them in a directory served by the same nginx and php-fpm instance. The allow-list that should restrict accepted file types is an empty array by default (file-upload/php/config.php:16), so the type check is a no-op and every extension is accepted. The filename sanitizer keeps the .php extension intact. Committed files land in /var/www/upload/server/php/files (file-upload/php/config.php:7), and the component’s nginx routes any URL ending in .php to php-fpm. An authenticated GET /server/php/files/.php then executes the uploaded code as www-data. Prior to version 26.06.1, in RBAC mode, the upload endpoint is reachable by the granular ROLE_UPLOAD role (nginx/lua/nginx_auth_helpers.lua:71), a role intended only for submitting capture files. As a result, a user holding the upload-only role runs arbitrary PHP as www-data inside the file-upload container. Version 26.06.1 fixes the issue.
Affected Products
CISA Malcolm
CISA
CISA Malcolm: <26.06.1
known_affected
Remediations
Vendor fix
Malcolm version 26.06.1 addresses this issue. For more information, see https://github.com/cisagov/Malcolm/pull/1026. (CVE-2026-55676)
https://github.com/cisagov/Malcolm/pull/1026
Relevant CWE: CWE-434 Unrestricted Upload of File with Dangerous Type
Metrics
| CVSS Version | Base Score | Base Severity | Vector String |
|---|---|---|---|
| 3.1 | 8.8 | HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 4.0 | 8.7 | HIGH | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N |
CVE-2026-63177
Malcolm is a network traffic analysis tool suite. Prior to version 26.07.0, role-based access control enforced in the Nginx OpenResty Lua layer evaluates the raw, unnormalized ngx.var.request_uri, while Nginx itself routes requests using the normalized path. An authenticated low-privilege user can prepend a traversal segment (for example /x/../upload/…) so that Nginx routes the request to a restricted backend while the Lua role check fails to match any rule and falls open, granting access it should deny. Version 26.07.0 fixes the issue.
Affected Products
CISA Malcolm
CISA
CISA Malcolm: <26.07.0
known_affected
Remediations
Vendor fix
Malcolm version 26.07.0 addresses these issues. For more information, see https://github.com/cisagov/Malcolm/pull/1043. (CVE-2026-63133, CVE-2026-63134, CVE-2026-63177)
https://github.com/cisagov/Malcolm/pull/1043
Relevant CWE: CWE-863 Incorrect Authorization
Metrics
| CVSS Version | Base Score | Base Severity | Vector String |
|---|---|---|---|
| 3.1 | 7.1 | HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N |
| 4.0 | 7.1 | HIGH | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:L/SI:L/SA:L |
CVE-2026-19670
Malcolm’s nginx Lua role-based access control (RBAC) layer decides whether an authenticated user may reach a role-restricted path (e.g. /htadmin, /auth, /admin_login, /arkime/api/esadmin, NetBox, upload endpoints) by pattern-matching the raw, percent-encoded request URI. Nginx itself, however, selects which location block actually serves the request using the percent-decoded, normalized URI. Because the RBAC check never percent-decodes its input, an authenticated low-privilege user can request an admin-only path using percent-encoding (e.g. /%68tadmin.php) and have nginx route it to the restricted location while the Lua RBAC gate evaluating the un-decoded raw string finds no matching restriction and grants access.
Affected Products
CISA Malcolm
CISA
CISA Malcolm: <=26.07.1
known_affected
Remediations
Vendor fix
Malcolm version 26.08.0 addresses this issue. For more information, see https://github.com/cisagov/Malcolm/security/advisories/GHSA-jr6p-63pg-hr6g. (CVE-2026-19670)
https://github.com/cisagov/Malcolm/security/advisories/GHSA-jr6p-63pg-hr6g
Relevant CWE: CWE-863 Incorrect Authorization
Metrics
| CVSS Version | Base Score | Base Severity | Vector String |
|---|---|---|---|
| 3.1 | 5.4 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N |
| 4.0 | 5.3 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N |
CVE-2026-19671
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.
Affected Products
CISA Malcolm
CISA
CISA Malcolm: <=26.07.1
known_affected
Remediations
Vendor fix
Malcolm version 26.08.0 addresses this issue. For more information, see https://github.com/cisagov/Malcolm/security/advisories/GHSA-f2v6-8cj4-mhr6. (CVE-2026-19671)
https://github.com/cisagov/Malcolm/security/advisories/GHSA-f2v6-8cj4-mhr6
Relevant CWE: CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)
Metrics
| CVSS Version | Base Score | Base Severity | Vector String |
|---|---|---|---|
| 3.1 | 6.5 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
| 4.0 | 7.1 | HIGH | 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 |
Acknowledgments
- pavanchow reported CVE-2026-63133, CVE-2026-63134, and CVE-2026-63177 to CISA.
- kah-ja, DeathRipper21 reported CVE-2026-55676 to CISA.
- tinyb0y reported CVE-2026-19670 and CVE-2026-19671 to CISA.
Legal Notice and Terms of Use
This product is provided subject to this Notification (https://www.cisa.gov/notification) and this Privacy & Use policy (https://www.cisa.gov/privacy-policy).
Recommended Practices
CISA recommends users take defensive measures to minimize the risk of exploitation of these vulnerabilities.
Minimize network exposure for all control system devices and/or systems, ensuring they are not accessible from the internet.
Locate control system networks and remote devices behind firewalls and isolating them from business networks.
When remote access is required, use more secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as the connected devices.
CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.
CISA also provides a section for control systems security recommended practices on the ICS webpage on cisa.gov/ics. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.
CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets.
Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov/ics in the technical information paper, ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation Strategies.
Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents.
CISA also recommends users take the following measures to protect themselves from social engineering attacks:
Do not click web links or open attachments in unsolicited email messages.
Refer to Recognizing and Avoiding Email Scams for more information on avoiding email scams.
Refer to Avoiding Social Engineering and Phishing Attacks for more information on social engineering attacks.
No known public exploitation specifically targeting these vulnerabilities has been reported to CISA at this time.
Revision History
- Initial Release Date: 2026-08-18
| Date | Revision | Summary |
|---|---|---|
| 2026-08-18 | 1 | Initial Publication |
