Cyber Resilience

CVE-2026-77129

Published
25 August 2026
Modified
26 August 2026
CVSS Score v4 7.7
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0023 14th percentile
Risk Priority 36 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-77129 is a high-severity Improper Neutralization of Special Elements Used in a Template Engine (CWE-1336) vulnerability in Typo3 (inferred from references). Its CVSS base score is 7.7 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Template Injection (T1221); ranked at the 14th 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 SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

The extension passes an editor-configurable email subject string directly into a Fluid template source without restriction. A backend user with edit access to the event plugin or Backend Module can supply Fluid ViewHelper syntax in this field to disclose sensitive…

more

data or execute TypoScript content objects. Exploitation of this issue requires an authenticated backend account with edit access to the event registration plugin or backend module.

CWE(s)
CWE-1336

Related Threats

MITRE ATT&CK Enterprise Techniques

T1221 Template Injection Stealth
Adversaries may create or modify references in user document templates to conceal malicious code or force authentication attempts.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-24724Shared CWE-1336
CVE-2026-35477Shared CWE-1336
CVE-2024-58303Shared CWE-1336
CVE-2025-64087Shared CWE-1336
CVE-2025-10380Shared CWE-1336
CVE-2026-41065Shared CWE-1336
CVE-2024-30372Shared CWE-1336
CVE-2026-54390Shared CWE-1336
CVE-2024-12583Shared CWE-1336
CVE-2024-57177Shared CWE-1336

Affected Assets

Typo3
—
inferred from references and description; NVD did not file a CPE for this CVE

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.3.2
  • V1.3.7
  • V1.3.10

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and static analysis can discover missing neutralization of template directives.

SI-10 Information Input Validation good match

Input validation rejects or sanitizes untrusted data before it reaches the template engine, stopping injection of special syntax.

SA-8 Security and Privacy Engineering Principles partial match

Security engineering principles require use of safe templating APIs and proper escaping of external input.

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 input neutralization in template engines to prevent injection.

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.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect template-injection flaws but does not itself implement neutralization controls.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle mandates input validation and sanitization that directly prevents template-injection weaknesses.

A.8.26 Application security requirements partial match
prevents

Application security requirements explicitly call for neutralizing special elements in template engines.

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

Secure architecture principles reduce the likelihood of unsafe template processing but do not prescribe specific neutralization techniques.

A.8.28 Secure coding partial match
prevents

Secure coding standards require proper escaping or sandboxing of template directives, directly mitigating CWE-1336.

References