44/100 CVSS 7.7 🔴 CVE ANALYSISPublished: July 6, 2026

Coder's session token leaked to arbitrary hosts via `coder open app` for external workspace apps

### Summary `coder open app` opens external workspace-app URLs without validating the scheme or host. When an external app URL contains the `$SESSION_TOKEN` placeholder the CLI replaces it with the user's real session token before handing the URL to the OS open handler. > **Note:** Practical exploitation requires the victim to run `coder open app` ...

7.7

CVSS Score

LOW

Threat Level

Priority /100

TBD

Exploited ITW

Monitor

CISA Status

Sources

🔵

HIGH-PRIORITY SECURITY ADVISORY — Priority Score: 44/100

CVSS 7.7 LOW. SENTINEL APEX recommends immediate patch evaluation. Intelligence from 1 confirmed source(s).

📋 Executive Summary

⚡ Analyst Assessment — SENTINEL APEX v4.0

This report analyzes CVE-2026-55431 affecting go github.com/coder/coder/v2 (CVSS 7.7, LOW severity). No confirmed in-the-wild exploitation at the time of writing; prioritize on exposure, privilege, and CVSS. Corroborated across 1 source(s): github_advisories. Verify all specifics against the primary sources linked below before acting.

Intelligence sources: github_advisories

🧮 Severity Anatomy — CVSS 3.1 vector, decoded from the primary record

The base score summarizes severity in one number; the vector explains why. Each row below is a direct read of the official CVSS vector — verifiable against the NVD record.

Metric	Value	What it means for defenders
Attack Vector	Network `AV:N`	Remotely exploitable across the network — internet-facing instances are directly at risk.
Attack Complexity	High `AC:H`	Depends on conditions outside attacker control (race, specific config) — harder to weaponize.
Privileges Required	Low `PR:L`	Requires basic user-level privileges.
User Interaction	Required `UI:R`	A user must click, open, or visit something — social engineering component.
Scope	Changed `S:C`	Impact extends beyond the vulnerable component — can affect other systems/security domains.
Confidentiality Impact	High `C:H`	Total loss of confidentiality — full data disclosure possible.
Integrity Impact	High `I:H`	Total loss of integrity — attacker can modify any data.
Availability Impact	None `A:N`	No availability impact.

⚠️ Business Impact Analysis

⚠️ go github.com/coder/coder/v2 users face material security risk requiring immediate remediation

🔗 Representative Attack Path

A typical attack path for this vulnerability class, mapped to MITRE ATT&CK. This is a representative model to guide detection and defense — not a claim of observed activity against a specific target. Confirm specifics against the primary sources below.

#	Phase	Attacker Action	MITRE
1	Reconnaissance	Attacker identifies exposed github.com/coder/coder/v2 instances via Shodan, Censys, or targeted scanning	`TA0043`
2	Initial Access	Exploitation of CVE-2026-55431 in go github.com/coder/coder/v2	`T1190`
3	Persistence	Backdoor, scheduled task, or new admin account created for persistent access	`T1053`
4	Command & Control	Attacker establishes persistent C2 channel using HTTPS or DNS tunneling	`T1071`
5	Impact / Objectives	Intellectual property theft, espionage, cryptomining, or preparation for future attack stage	`T1657`

⚠ Deep Dive Analysis

This high-severity vulnerability in go github.com/coder/coder/v2 (CVSS 7.7) represents a significant attack surface. SENTINEL APEX assesses exploitation to be technically feasible with moderate effort. Organizations running github.com/coder/coder/v2 in internet-facing or privileged positions face immediate risk.

SENTINEL APEX URGENCY: ELEVATED. Score: 44/100 LOW. Patch before exploitation activity begins.

🧠 Structured Intelligence Assessment

SENTINEL APEX analytical tradecraft separates verified fact from labeled assessment and states intelligence gaps explicitly. Confidence reflects evidentiary support, not certainty.

✔ Verified Facts

Affected CVE(s): CVE-2026-55431, CVE-2026-55431.
Affected technology: go github.com/coder/coder/v2.
CVSS base score of 7.7 assigned by an authoritative source.
1 indicator(s) of compromise extracted from source reporting.

🕸️ Correlated Observations

Vendor go has been targeted in 6 prior CYBERDUDEBIVASH reports (recurring target)
Product github.com/coder/coder/v2 has been targeted in 6 prior CYBERDUDEBIVASH reports (recurring target)
Related prior intelligence: cve-2026-55427-go-github-com-coder-coder-v2 (2 shared entities), cve-2026-55428-go-github-com-coder-coder-v2 (2 shared entities), cve-2026-55075-go-github-com-coder-coder-v2 (2 shared entities), cve-2026-55076-go-github-com-coder-coder-v2 (2 shared entities), cve-2026-55077-go-github-com-coder-coder-v2 (2 shared entities)

🧩 Analyst Assessments

MEDIUM CONF Technical severity is assessed as high (CVSS 7.7); realized business impact depends on asset exposure and data classification.

❓ Intelligence Gaps

In-the-wild exploitation is unconfirmed as of this report.
Attribution to a specific threat actor is not established by the available evidence.
The source lacks sufficient technical detail for confident MITRE ATT&CK mapping.

🔮 Forward Outlook

MEDIUM CONF Given the repeated targeting pattern, further activity against this vendor/sector is probable.

🧬 Prior Intelligence Context

This report is correlated against CYBERDUDEBIVASH SENTINEL APEX's persistent analyst memory. The following entities have been tracked in prior intelligence:

Vendor go — previously observed 6 times in CYBERDUDEBIVASH intelligence since 2026-07-06 (recent: cve-2026-55076-go-github-com-coder-coder-v2, cve-2026-55077-go-github-com-coder-coder-v2)
Product github.com/coder/coder/v2 — previously observed 6 times in CYBERDUDEBIVASH intelligence since 2026-07-06 (recent: cve-2026-55076-go-github-com-coder-coder-v2, cve-2026-55077-go-github-com-coder-coder-v2)

🎯 MITRE ATT&CK Mapping

Category	Mapping
Primary Tactic	ML Attack Staging
Primary Technique	AML.T0040 — ML Attack Staging
Sub-Technique	AML.T0000 — AI/ML System Enumeration
Weakness (CWE)	CWE-522
Intel Type	🔴 CVE ANALYSIS
Source(s)	github_advisories

🔴 CVE Reference

CVE ID	Reference	Score
CVE-2026-55431	NVD →	7.7
CVE-2026-55431	NVD →	7.7

🏷️ Indicators of Compromise — Enriched IOC Feed

Normalized IOCs with confidence scoring. Block immediately across all enforcement points. SOC Pro subscribers receive enriched IOC bundles with full attribution and STIX/TAXII feeds.

Indicator Value	Type	Confidence	First Seen
https://attacker.example/?t=$SESSION_TOKEN`.	url	82%	2026-07-06

🔍 Detection Rules — Sigma (SIEM)

Deploy to Splunk, Elastic, Microsoft Sentinel, or QRadar. SOC Pro subscribers receive pre-compiled SIEM-native query packs updated with each pipeline run.

Sigma YAMLtitle: CVE-2026-55431 Exploitation Attempt — go github.com/coder/coder/v2
id: d9f34fbccbd400fc-e016
status: experimental
description: Detects exploitation of CVE-2026-55431 in go github.com/coder/coder/v2. Priority: LOW. Score: 44/100
author: CYBERDUDEBIVASH SENTINEL APEX v4.0 (bivash@cyberdudebivash.com)
date: 2026-07-06
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2026-55431
    - https://blog.cyberdudebivash.in/
tags:
    - attack.initial_access
    - attack.t1190
    - cve-2026-55431
    - cve-2026-55431
logsource:
    category: webserver
detection:
    keywords:
        - 'CVE-2026-55431'
        - 'CVE-2026-55431'
        - 'cve-2026-55431'
    condition: keywords
falsepositives:
    - Security scanners
level: medium

📡 Detection Rules — YARA (Endpoint)

Deploy to endpoint detection platforms. Enterprise subscribers receive tuned, FP-validated YARA rule packs.

YARArule CVE_2026_55431_Exploitation {
    meta:
        description = "Detects artifacts related to CVE-2026-55431 exploitation in go github.com/coder/coder/v2"
        author      = "CYBERDUDEBIVASH SENTINEL APEX v4.0"
        date        = "2026-07-06"
        severity    = "HIGH"
        cvss        = "7.7"
        priority    = "44/100"
        threat_level = "LOW"
        reference   = "https://nvd.nist.gov/vuln/detail/CVE-2026-55431"
    strings:
        $id_str  = "CVE-2026-55431" ascii nocase
        $product = "github_com_coder_coder_v2" ascii nocase wide
    condition:
        any of them
}

🧠 Multi-Platform Detection Engineering

Evidence-driven detections mapped to MITRE ATT&CK, generated by the SENTINEL APEX Detection Engine — one validated rule per technique across SIEM, EDR, and network platforms. SOC Pro subscribers receive these as deploy-ready rule packs with each pipeline run.

Network Detection — Suricata

Suricata IDS/IPSalert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CYBERDUDEBIVASH SENTINEL APEX - malicious URL https://attacker.example/?t=$SESSION_TOKEN`."; http.host; content:"attacker.example"; nocase; http.uri; content:"/?t=$SESSION_TOKEN`."; nocase; classtype:trojan-activity; sid:9000001; rev:1;)

🎯 Multi-Audience Intelligence Products

This single analysis is packaged for every stakeholder — from the boardroom to the SOC — plus a machine-readable feed for API and MSSP integration. Enterprise & SOC Pro subscribers receive these as structured deliverables.

🏛 Executive Advisory — CISO / Security Leadership

Affected CVE(s): CVE-2026-55431, CVE-2026-55431.
Affected technology: go github.com/coder/coder/v2.
CVSS base score of 7.7 assigned by an authoritative source.
1 indicator(s) of compromise extracted from source reporting.

Owner	Decision	Timeline
CISO / SOC Lead	Authorize response activation and detection deployment	Within 24h
Vulnerability Mgmt	Prioritize remediation/patching of go assets	Within 7 days
Legal / Privacy	Assess regulatory notification obligations if in-scope data is at risk	Within 48h

📋 Board Brief

A high-severity cyber threat affects go github.com/coder/coder/v2.
Technical severity is rated 7.7/10.
Primary exposure is operational disruption, data loss, and potential regulatory liability (e.g. GDPR, NIS2, DORA, SOC 2) where in-scope systems are affected.
Mitigation depends on vendor guidance and compensating controls.
Recommended posture: authorize prioritized remediation and confirm detection coverage with the security team.

🛡 SOC Bulletin

Severity HIGH · Detection coverage: 0 technique(s) across behavioral analytics · 1 network rule(s)

P0: Block all 1 IOC(s) at firewall, proxy, DNS, and EDR simultaneously.
P1: Load the 1 Suricata network rule(s) at IDS/IPS choke points.
P1: Sweep 14 days of telemetry for the mapped ATT&CK techniques.
P2: Update threat-intel platform and downstream detection feeds with confirmed indicators.

⎋ Machine-readable intelligence: this report is available as a structured JSON package (MITRE ATT&CK, IOCs, multi-platform detections, analyst assessments) at /api/intel/products/cve-2026-55431-go-github-com-coder-coder-v2.json — built for SIEM, SOAR, and MSSP integration.

🛡️ SOC Response Playbook

1IMMEDIATE (0-1hr): Identify all instances of github.com/coder/coder/v2 in your environment via CMDB/asset inventory
2IMMEDIATE: Block all 1 IOCs in this report at firewall, proxy, DNS, and EDR simultaneously
3IMMEDIATE (0-1hr): Apply vendor patch — no maintenance window exception for LOW threats
4IMMEDIATE (1-2hr): If no patch available: implement WAF rules, ACLs, or network-level compensating controls
5SHORT-TERM (2-4hr): Deploy Sigma detection rule to SIEM — validate alert generation in test environment
6SHORT-TERM (4-8hr): Review logs for exploitation indicators (anomalous github.com/coder/coder/v2 requests, error spikes)
7SHORT-TERM (8-24hr): Hunt for post-exploitation: new admin accounts, scheduled tasks, lateral movement
8MONITOR: Subscribe to go security advisories for patch updates
9ONGOING: Track SENTINEL APEX intelligence feed for follow-on campaigns targeting github.com/coder/coder/v2

📎 Intelligence References

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⚡ CYBERDUDEBIVASH SENTINEL APEX v4.0

Intelligence report generated by CYBERDUDEBIVASH SENTINEL APEX v4.0
Report ID: SENTINEL-CVE-2026-55431-2026-07-06 | Priority: 44/100 LOW | Sources: 1
© 2026 CYBERDUDEBIVASH PRIVATE LIMITED
Republication requires written attribution to CYBERDUDEBIVASH SENTINEL APEX

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