Description

Partial string comparison in Windows HTTP Protocol Stack allows an unauthorized attacker to perform tampering over an adjacent network.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.5",
  "pubDate": "2026-08-11T17:18:27.367Z",
  "pubdate": "2026-08-11T17:18:27.367Z",
  "executiveSummary": "A tampering vulnerability exists within the Windows HTTP Protocol Stack, specifically stemming from improper partial string comparison operations.\nThis security flaw allows an unauthorized attacker positioned on an adjacent network to execute unauthorized data tampering and integrity violations against target systems.\nThe affected product is the Windows HTTP Protocol Stack, which handles core HTTP request processing and web services infrastructure for the operating system.\nThe risk implications are significant, as successful exploitation undermines the integrity of network communications, potentially leading to unauthorized modification of data in transit or application-level state manipulation.\nThe attacker capabilities are constrained to unauthorized execution within the scope of an adjacent network, requiring local segment access to interact directly with the vulnerable stack.\nNo specific elevated privileges or explicit authentication mechanisms are required for an attacker to initiate the exploitation sequence, provided network adjacency is established.",
  "technicalDetails": "The vulnerability resides in the Windows HTTP Protocol Stack component responsible for parsing, evaluating, and matching HTTP header strings and URIs.\nThe root cause of the vulnerability is the implementation of insecure partial string comparison routines. When the protocol stack processes incoming HTTP requests, it relies on string comparison functions that evaluate only a subset of expected input characters or fail to enforce strict boundary checks and full-string validation.\nThis logic flaw enables an attacker to craft specially designed HTTP requests containing carefully manipulated payloads that bypass validation filters or cause the stack to misinterpret distinct header values and routing paths.\nExploitation occurs over an adjacent network where the attacker transmits malicious HTTP packets directly to the target system hosting the vulnerable Windows HTTP Protocol Stack.\nDuring the attack flow, the protocol stack receives the malformed packet and executes the vulnerable partial string comparison algorithm. Because the comparison logic incorrectly matches the partial string against internal control structures or routing directives, the stack processes the anomalous request as legitimate or maps it to an unintended handler.\nThis discrepancy allows the adversary to bypass security controls, inject unauthorized parameters, or cause data tampering within the HTTP processing pipeline.\nThe network exposure is limited to adjacent network boundaries, meaning the attacker must be on the same local network segment (such as a local subnet or layer 2 domain) to intercept or inject traffic destined for the vulnerable stack.\nAuthentication and privilege requirements are minimal; an unauthorized threat actor with basic network connectivity to the adjacent segment can initiate the attack without possessing valid credentials or administrative privileges on the target host.\nThe post-exploitation impact includes compromised data integrity, potential spoofing of HTTP traffic, and the capability to manipulate server-side request handling, which may facilitate secondary application-layer attacks or service disruption."
}