Cyber Resilience

CVE-2026-92238

Published
15 September 2026
Modified
22 September 2026
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0018 8th percentile
Risk Priority 69 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-2026-92238 is a critical-severity HTTP Request/Response Smuggling (CWE-444) vulnerability in Mozilla (inferred from references). Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

OWASP Top 10 for Web (2025)

A06:2025 Insecure Design

EU & UK References

Vulnerability Data

A maliciously constructed mail header could lead to multiple fields being parsed as one, or potential memory safety violations. This vulnerability was fixed in Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

CWE(s)
CWE-444

Related Threats

MITRE ATT&CK Enterprise Techniques

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 →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

Affected Assets

Mozilla
—
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)
  • V4.1.3
  • V4.2.4
  • V1.5.3
  • V4.1.1

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.

DE.CM-01 partial match
prevents

Network monitoring can detect smuggling attempts via anomalous HTTP traffic or logs, while eliminating the inconsistency directly aids detection of such events.

PR.IR-01 partial match
prevents

Network protections can enforce consistent HTTP proxy/firewall behavior to block smuggling, and removing the weakness helps prevent unauthorized access via request smuggling.

PR.PS-01 partial match
prevents

Configuration management can enforce uniform HTTP parsing rules across intermediaries, directly mitigating inconsistent interpretation.

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.8.20 Networks security partial match
degrades

Network security controls can enforce consistent HTTP parsing and proxy behavior that mitigates request smuggling.

A.8.21 Security of network services partial match
degrades

Secure network services include hardening proxies and gateways against inconsistent HTTP interpretation.

A.8.25 Secure development life cycle partial match
prevents

Secure SDLC practices require threat modeling and testing for HTTP parsing inconsistencies in intermediaries.

A.8.26 Application security requirements partial match
prevents

Application security requirements can mandate strict HTTP message validation and canonicalization.

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

Secure architecture principles include consistent protocol handling and defense-in-depth for proxies.

A.8.28 Secure coding partial match
prevents

Secure coding standards can require strict HTTP header and request validation to prevent smuggling.

References