Cyber Resilience

CVE-2026-39826

Golang Go ≤ 1.25.10

Published
07 May 2026
Modified
17 June 2026
Patch / advisory
View advisory
CVSS Score v3.1 6.1
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
EPSS Score 0.0037 30th percentile
Risk Priority 35 floored blend · peak EPSS

Summary

CVE-2026-39826 is a medium-severity Improper Encoding or Escaping of Output (CWE-116) vulnerability in Golang Go. Its CVSS base score is 6.1 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 30th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SI-15 (Information Output Filtering) and AC-4 (Information Flow Enforcement) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

If a trusted template author were to write a <script> tag containing an empty 'type' attribute or a 'type' attribute with an ASCII whitespace, the execution of the template would incorrectly escape any data passed into the <script> block.

CWE(s)
CWE-116

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1059.007 JavaScript Execution
Adversaries may abuse various implementations of JavaScript for execution.
attack.mitre.org →
Why these techniques?

Vulnerability in template escaping allows arbitrary JavaScript injection inside <script> blocks, directly enabling client-side code execution via public web apps.

Confidence: MEDIUM · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2026-39823Same product: Golang Go
CVE-2026-32289Same product: Golang Go
CVE-2026-39825Same product: Golang Go
CVE-2026-27142Same product: Golang Go
CVE-2025-68121Same product: Golang Go
CVE-2026-32280Same product: Golang Go
CVE-2025-61726Same product: Golang Go
CVE-2026-27143Same product: Golang Go
CVE-2026-27139Same product: Golang Go
CVE-2025-47906Same product: Golang Go

Affected Assets

golang
go
≤ 1.25.10 · 1.26.0 — 1.26.3

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • SI-15 Information Output Filtering
  • SI-10 Information Input Validation
  • AC-4 Information Flow Enforcement
Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.1.2
  • V1.2.1
  • V1.2.3

Mitigating Controls (NIST 800-53 r5) AI

SI-15 Information Output Filtering good match
prevent

Directly requires output filtering/encoding of untrusted data inserted into templates, preventing the incorrect escaping inside <script> blocks described by the CVE.

SI-10 Information Input Validation partial match
prevent

Requires validation and sanitization of data and template inputs before processing, which can catch or block the malformed type-attribute cases that defeat escaping.

AC-4 Information Flow Enforcement partial match
prevent

Enforces information flow rules that can mandate proper context-aware encoding when data crosses into script contexts, mitigating the CWE-116 flaw.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require proper output encoding to prevent injection and message malformation.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.28 Secure coding mostly match
prevents

Secure coding standards explicitly require correct output encoding and escaping to preserve message structure.

A.8.29 Security testing in development and acceptance mostly match
detects

Security testing can detect missing or incorrect encoding but does not itself implement the control.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle mandates output encoding/escaping practices that directly prevent improper encoding.

A.8.26 Application security requirements partial match
prevents

Application security requirements include explicit rules for safe output handling and encoding.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles reduce the likelihood of missing encoding but do not prescribe the actual technique.

References