Security Digest · Vulnerability record
CVE-2026-35580: Emissary has GitHub Actions Shell Injection via Workflow Inputs
Emissary is a P2P based data-driven workflow engine.
CVSS 9.1 Critical EPSS 0.7% · p52
Should you act?
Critical, preconditions apply
Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.7%, percentile 52: FIRST’s model estimates a 0.7% chance of exploitation activity in the next 30 days, higher than 52% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Needs an account (high (admin)). Exposure depends on who can log in.
- Only applies if your dependency tree includes
gov.nsa.emissary:emissary(Maven) < 8.39.0, fixed in 8.39.0. Check your lockfile, including transitive dependencies.
What it is
Emissary is a P2P based data-driven workflow engine. Prior to 8.39.0, GitHub Actions workflow files contained shell injection points where user-controlled workflowdispatch inputs were interpolated directly into shell commands via ${{ }} expression syntax. An attacker with repository write access could inject arbitrary shell commands, leading to repository poisoning and supply chain compromise affecting all downstream users. This vulnerability is fixed in 8.39.0.
From the GitHub advisory
Summary
Three GitHub Actions workflow files contained 10 shell injection points where user-controlled workflowdispatch inputs were interpolated directly into shell commands via ${{ }} expression syntax. An attacker with repository write access could inject arbitrary shell commands, leading to repository poisoning and supply chain compromise affecting all downstream users.
Affected Files
| Workflow file | Injection points | |------------------------------------------|------------------| | .github/workflows/maven-version.yml | 4 | | .github/workflows/cherrypick.yml | 5 | | .github/workflows/maven-release.yml | 1 |
Details
Weakness type: CWE-77.
Product: gov.nsa.emissary:emissary (Maven) · Assigned by: GitHub_M · Published: 2026-04-07
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| Maven | gov.nsa.emissary:emissary | < 8.39.0 | 8.39.0 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| NationalSecurityAgency | emissary | < 8.39.0 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_M | 3.1 | 9.1 Critical | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H |
| GitHub | 3.1 | 9.1 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: high (admin)
- User interaction: none
- Scope: changed (can affect other components)
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none, automatable no, technical impact total.
- FIRST EPSS (model of 2026-10-21): 0.69% probability of exploitation activity in the next 30 days; percentile 52.
Timeline
- — CVE record last updated
- — CVE record published by GitHub_M
- — GitHub-reviewed advisory GHSA-3g6g-gq4r-xjm9 published (critical)
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- GitHub Advisory GHSA-3g6g-gq4r-xjm9 github.com
- CVE.org record CVE-2026-35580 cve.org
- NVD entry CVE-2026-35580 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- github.com github.com
- github.com github.com