Cyber Resilience

CVE-2023-4639

Published
17 November 2024
Modified
15 April 2026
CVSS Score v3.1 7.4
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS Score 0.011 63th percentile
Risk Priority 63 floored blend · peak EPSS

Summary

CVE-2023-4639 is a high-severity HTTP Request/Response Smuggling (CWE-444) vulnerability. Its CVSS base score is 7.4 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 37% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SC-7 (Boundary Protection) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

A flaw was found in Undertow that causes incorrect parsing of cookies containing certain value-delimiting characters in incoming HTTP requests. The affected component is the Undertow web server used in Red Hat middleware products. The vulnerability, tracked as CVE-2023-4639 and assigned CWE-444, permits construction of malicious cookie values that can exfiltrate HttpOnly cookies or inject arbitrary additional cookies, resulting in impacts to data confidentiality and integrity. It carries a CVSS 3.1 base score of 7.4.

An unauthenticated remote attacker can exploit the issue over the network by sending crafted requests containing specially formatted cookies. Successful exploitation allows the attacker to read or overwrite sensitive session or authentication cookies without requiring user interaction, potentially leading to unauthorized access or modification of application data.

Red Hat has published multiple advisories (RHSA-2024:1674, RHSA-2024:1675, RHSA-2024:1676, RHSA-2024:1677, and RHSA-2024:2763) that address the flaw through updated Undertow packages. The EPSS score has remained flat at 0.0736 with no material increase since disclosure.

OWASP Top 10 for Web (2025)

A06:2025 Insecure Design

EU & UK References

Vulnerability Data

A flaw was found in Undertow, which incorrectly parses cookies with certain value-delimiting characters in incoming requests. This issue could allow an attacker to construct a cookie value to exfiltrate HttpOnly cookie values or spoof arbitrary additional cookie values, leading…

more

to unauthorized data access or modification. The main threat from this flaw impacts data confidentiality and integrity.

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.

CVEs Like This One

CVE-2026-40562Shared CWE-444
CVE-2026-42581Shared CWE-444
CVE-2025-55018Shared CWE-444
CVE-2024-27185Shared CWE-444
CVE-2025-1386Shared CWE-444
CVE-2023-37276Shared CWE-444
CVE-2025-14523Shared CWE-444
CVE-2025-32094Shared CWE-444
CVE-2025-49826Shared CWE-444
CVE-2025-6999Shared CWE-444

Affected Assets

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 800-53 r5) AI

SC-7 Boundary Protection partial match

Boundary protection at external interfaces can enforce consistent HTTP request/response parsing rules between intermediaries and endpoints.

SI-10 Information Input Validation partial match

Validating HTTP inputs at the intermediary prevents malformed messages from being interpreted inconsistently downstream.

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-01 mostly match
prevents

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

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.

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 HTTP request smuggling vulnerabilities in intermediary components.

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.

References