Ech0: ParseAcceptLanguage `_` separator bypass enables ~70x CPU amplification via Accept-Language header in i18n.Middleware
### Summary Ech0's i18n middleware runs on every HTTP request and constructs a fresh `*goi18n.Localizer` from the raw `Accept-Language` header without imposing any size or shape filter. `goi18n.NewLocalizer` calls `golang.org/x/text/language.ParseAcceptLanguage` on the value internally. The underlying parser has quadratic-time behaviour on long lis...
CVSS 7.5 LOW. SENTINEL APEX recommends immediate patch evaluation. Intelligence from 1 confirmed source(s).
๐ Executive Summary
This report analyzes GHSA-0c7bb93a25471f15 affecting go github.com/lin-snow/ech0 (CVSS 7.5, 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.
โ ๏ธ Business Impact Analysis
- โ ๏ธ Authentication bypass โ all access controls circumvented
๐ 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 โ 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/lin-snow/ech0 instances via Shodan, Censys, or targeted scanning | TA0043 |
2 |
Initial Access | Unauthenticated exploitation โ no credentials required. Single HTTP request sufficient | 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 |
โ Deep Dive Analysis
This high-severity vulnerability in go github.com/lin-snow/ech0 (CVSS 7.5) represents a significant attack surface. SENTINEL APEX assesses exploitation to be technically feasible with moderate effort. Organizations running github.com/lin-snow/ech0 in internet-facing or privileged positions face immediate risk.
SENTINEL APEX URGENCY: ELEVATED. Score: 44/100 LOW. Patch before exploitation activity begins.
๐ง Structured Intelligence Assessment
SENTINEL APEX analytical tradecraft separates verified fact from labeled assessment and states intelligence gaps explicitly. Confidence reflects evidentiary support, not certainty.
โ Verified Facts
- Affected technology: go github.com/lin-snow/ech0.
- CVSS base score of 7.5 assigned by an authoritative source.
- 1 indicator(s) of compromise extracted from source reporting.
๐ธ๏ธ Correlated Observations
- Vendor go has been targeted in 22 prior CYBERDUDEBIVASH reports (recurring target)
๐งฉ Analyst Assessments
- MEDIUM CONF Technical severity is assessed as high (CVSS 7.5); realized business impact depends on asset exposure and data classification.
โ 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.
๐ฎ Forward Outlook
- MEDIUM CONF Given the repeated targeting pattern, further activity against this vendor/sector is probable.
๐งฌ 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 โ previously observed 22 times in CYBERDUDEBIVASH intelligence since 2026-07-06 (recent: cve-2026-50141-go-go-woodpecker-ci-org-woodpecker-v3, tsdproxy-x-forwarded-for-header-injection-allows-ip-spoofin)
๐ฏ MITRE ATT&CK Mapping
| Category | Mapping |
|---|---|
| Primary Tactic | Initial Access |
| Primary Technique | T1190 โ Exploit Public-Facing Application |
| Sub-Technique | T1078 โ Valid Accounts |
| Weakness (CWE) | CWE-770 |
| Intel Type | ๐ด CVE ANALYSIS |
| Source(s) | github_advisories |
๐ท๏ธ Indicators of Compromise โ 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 |
|---|---|---|---|
| golang.org | domain | 75% | 2026-07-14 |
๐ Detection Rules โ Sigma (SIEM)
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๐ก Detection Rules โ YARA (Endpoint)
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๐ง Multi-Platform Detection Engineering
Evidence-driven detections mapped to MITRE ATT&CK, generated by the SENTINEL APEX Detection Engine โ 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 โ Suricata
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๐ Executive Advisory โ CISO / Security Leadership
- Affected technology: go github.com/lin-snow/ech0.
- CVSS base score of 7.5 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 |
๐ Board Brief
- A high-severity cyber threat affects go github.com/lin-snow/ech0.
- Technical severity is rated 7.5/10.
- 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.
๐ก SOC Bulletin
Severity HIGH ยท Detection coverage: 0 technique(s) across behavioral analytics ยท 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.
๐ก๏ธ SOC Response Playbook
- 1IMMEDIATE (0-1hr): Identify all instances of github.com/lin-snow/ech0 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 โ 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 โ validate alert generation in test environment
- 6SHORT-TERM (4-8hr): Review logs for exploitation indicators (anomalous github.com/lin-snow/ech0 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/lin-snow/ech0
๐ Intelligence References
- github.com/advisories/GHSA-mqxv-9rm6-w8qc
- github.com/lin-snow/Ech0/security/advisories/GHSA-mqxv-9rm6-w8qc
- github.com/advisories/GHSA-mqxv-9rm6-w8qc
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Report ID: SENTINEL-GHSA-0c7bb93a25471f15-2026-07-14 | Priority: 44/100 LOW | Sources: 1
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