CVE-2026-77156 — ast-cli: Path traversal in tar extraction on Linux/macOS allows writes outside the install directory
Incomplete validation of extracted archive entry paths in ast-cli's tar extraction logic on Linux and macOS (used when installing the Vorpal ASCA real-time engine and the SCA Resolver) would allow a malicious tar archive containing absolute or traversal path entries to write files outside the install directory. Windows builds were not affected, as the Windows extractor performs this path validation. Exploitation required substituting the archive served at "download.checkmarx.com". An attacker able to compromise that server and replace the archive could write arbitrary, executable files to arbitrary filesystem paths via this path traversal. Extraction now validates that each entry's destination path resolves within the working directory and rejects absolute paths.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.3% (30-day exploitation probability)+4
- Technical severity (medium)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Checkmarx Github.com/checkmarx/ast-cli).
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Exploitation requires user interaction: tighten email/web filtering and warn affected users.
- Search available logs for exploit probes matching the vulnerability class (file handling), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Checkmarx | Github.com/checkmarx/ast-cli | < 2.3.51 | Vulnerable | CVE Program (cve.org) e CISA ADP |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 6.3 | CVSS 4.0 | Medium | — | — | 596c5446-0ce5-4ba2-aa66-48b3b757a647 via NIST National Vulnerability Database |
| 6.3 | CVSS 4.0 | Medium | — | — | Checkmarx via CVE Program (cve.org) e CISA ADP |
| 6.4 | CVSS 3.1 | Medium | 0.5 | 5.9 | 596c5446-0ce5-4ba2-aa66-48b3b757a647 via NIST National Vulnerability Database |
| 6.4 | CVSS 3.1 | Medium | — | — | Checkmarx via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H (score shown at the top: 596c5446-0ce5-4ba2-aa66-48b3b757a647) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
EPSS over time FIRST
Oct 23, 2026 → Oct 28, 2026 · 6 reading(s) · max 0.35%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
- Monitor file creation in web directories and paths with traversal sequences (../).
Timeline
What happened to this CVE, newest first.
- 2026
- Source status changed · Received → Deferred
- Affected products added · checkmarx/github.com/checkmarx/ast-cli
- Record published
- CVSS changed · 6.4
- Source status changed · → Received
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× References added · Oct 22, 2026 – Oct 22, 2026
- 1× Official description updated · Oct 22, 2026 – Oct 22, 2026
References
2 on the record
Elsewhere on this site
Related CVEs (same products)
- Medium CVE-2026-77157 ast-cli: Auto-update downloads are not verified against a checksum before execution 6d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No fixed version, patch or mitigation documented.
- No CISA SSVC assessment.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-77156 is "ast-cli: Path traversal in tar extraction on Linux/macOS allows writes outside the install directory", rated Medium. It affects Github.com/checkmarx/ast-cli (Checkmarx); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 6.4 describes technical severity. EPSS 0.35% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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