CVE-2026-123864
Description
A flaw was found in Node.js. An unauthenticated remote attacker can exploit a re-entrancy vulnerability in the HTTPS server to cause memory corruption and read memory belonging to other connections. Under specific request handling conditions, processing incoming encrypted data while the HTTP parser is active causes freed or out-of-bounds heap memory to be read and returned to the client. This flaw leads to information disclosure, potentially exposing sensitive data such as other users' requests and Transport Layer Security (TLS) private keys.
Statement
This vulnerability is rated as Important rather than Moderate because an unauthenticated remote attacker can trigger heap memory corruption across concurrent sessions, potentially leaking sensitive data such as private cryptographic keys or request payloads belonging to other users. However, successful exploitation requires high attack complexity, as the target application must implement specific streaming and header-flushing behaviors during request body processing. Node.js deployments serving unencrypted HTTP or terminating TLS at an external gateway remain unaffected by this flaw.
Mitigation
Offload TLS termination to a trusted reverse proxy or load balancer, and configure the Node.js application to serve traffic over cleartext HTTP bound only to localhost (127.0.0.1), as cleartext HTTP is not affected by this flaw.
If TLS must remain terminated by the Node.js process, restrict network access to trusted hosts using firewall rules to limit exposure:
# firewall-cmd --permanent --zone=internal --add-port=<PORT>/tcp
# firewall-cmd --permanent --zone=public --remove-port=<PORT>/tcp
# firewall-cmd --reload
Caveats:
Restricting access to trusted networks or localhost prevents untrusted remote clients from reaching the service. Offloading TLS requires reconfiguring traffic routing and reverse proxy endpoints.
Warning: Modifying firewall configurations and running `firewall-cmd --reload` will reload firewall rule sets and may cause momentary disruptions to active connections.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.4 | N/A | 8.1 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | High |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Changed |
| Confidentiality | High | N/A | Low |
| Integrity Impact | None | N/A | Low |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H
cve.org: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Unexpected State
Exploitation of this weakness can leave the application in an unexpected state and cause variables to be reassigned before the first invocation has completed. This may eventually result in memory corruption or unexpected code execution.
Frequently Asked Questions
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