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Public proof of conceptFix available

CVE-2026-35580

A public proof of concept exists; no exploitation attested.

  • Published2026-04-07
  • Fixed in8.39.0
  • WeaknessCWE-77

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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 workflow_dispatch 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.

Timeline

dates in UTC
  1. 2026-04-0717:16CVE publishedNVD
  2. 2026-10-2319:23First public proof of conceptPoC-in-GitHub

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-35580?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-35580?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

OSV · NVD
emissary
BranchAffectedFixed in
8.39< 8.39.08.39.0
Nsa emissary
BranchAffectedFixed in
8.38≥ 5.10.0, ≤ 8.38.0no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

  1. Update emissary to 8.39.0

Advisories and patches

Detection

read 2026-10-23 19:25 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
1 repository, unverifiedpvharmo2/gha-lab-ed7a1740c4
PoC-in-GitHub

Sources

  • NVDCVE recordread 2026-10-23
  • CISA-ADPSSVC decisionnone2026-04-07
  • OpenCVESSVC decisionnone—
  • CNACVSS 3.19.1read 2026-10-23
  • CNAweakness (CWE)CWE-77read 2026-10-23
  • FIRST EPSSEPSS score0.7 %2026-10-23
  • PoC-in-GitHubproof of concept1read 2026-10-23
  • OSVaffected packages—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Published
2026-04-07
Last Modified
2026-06-17
NVD status
Analyzed

Frequently asked questions

What is CVE-2026-35580?

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 workflow_dispatch 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.

Is CVE-2026-35580 actively exploited?

Active exploitation of CVE-2026-35580 has not been confirmed. Its EPSS score was 0.7% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-35580?

CVE-2026-35580 has a CVSS v3 base score of 9.1 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H.

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