CVE-2026-12549
Received Received - Intake
HTTP 206 Range Request Negative Start Value in Apache HTTP Server

Publication date: 2026-06-22

Last updated on: 2026-06-22

Assigner: Red Hat, Inc.

Description
The fix for CVE-2026-2443 was regressed by a subsequent rework commit that replaced specific overflow checks with a general signed comparison. When a client sends a Range request with a suffix length exceeding the content size, the resulting negative start value is not properly clamped, leading to malformed HTTP 206 responses and log flooding.
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Meta Information
Published
2026-06-22
Last Modified
2026-06-22
Generated
2026-06-22
AI Q&A
2026-06-22
EPSS Evaluated
N/A
NVD
CVE-2026-12549
EUVD
EUVD-2026-38279
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
redhat libsoup *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-805 The product uses a sequential operation to read or write a buffer, but it uses an incorrect length value that causes it to access memory that is outside of the bounds of the buffer.
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Executive Summary

CVE-2026-12549 is a security vulnerability in the libsoup library, specifically in the SoupServer component. It is an incomplete fix for a previous vulnerability (CVE-2026-2443) related to range suffix overflow. The issue arises when a client sends an HTTP Range request with a suffix length that exceeds the content size. This causes a negative start value that is not properly clamped, leading to malformed HTTP 206 Partial Content responses and flooding of logs.

Impact Analysis

This vulnerability can impact systems by causing malformed HTTP 206 responses, which may disrupt normal server-client communication. Additionally, it can lead to log flooding, potentially overwhelming logging systems and making it harder to detect other issues or attacks. The CVSS score indicates a medium severity with potential limited confidentiality and availability impacts.

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