CVE-2026-12549
MediumCVSS 4.8Exploitation Probability (EPSS)
Low risk24th percentile - higher than 24% of all known CVEs
Summary
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.
Risk Assessment
The organization is exposed to potential DoS attacks via log flooding and the risk of serving malformed data in HTTP 206 responses, which may affect service integrity and availability.
Recommendation
Immediately update the HTTP server to a version containing the correct fix for CVE-2026-12549 and ensure no other changes have reverted the overflow protections.
Other vulnerabilities in Apache HTTP Server
See all- CVE-2017-9798High
Apache httpd allows remote attackers to read secret data from process memory if the Limit directive can be set in a user's .htaccess file, or if httpd.conf has certain misconfigurations. This affects the Apache HTTP Server through 2.2.34 and 2.4.x through 2.4.27.
- CVE-2016-8743High
Apache HTTP Server, in all releases prior to 2.2.32 and 2.4.25, was liberal in the whitespace accepted from requests and sent in response lines and headers. This acceptance of different behaviors represented a security concern when httpd participates in any chain of proxies or interacts with back-end application servers.
- CVE-2016-5387High
Apache HTTP Server through 2.4.23 does not protect applications from untrusted client data in the HTTP_PROXY environment variable, allowing remote attackers to redirect an application's outbound HTTP traffic to an arbitrary proxy server via a crafted Proxy header in an HTTP request.
- CVE-2016-4979High
Apache HTTP Server versions 2.4.18 to 2.4.20, when mod_http2 and mod_ssl are enabled, improperly recognize the 'SSLVerifyClient require' directive for HTTP/2 request authorization. This allows remote attackers to bypass intended access restrictions.
- CVE-2024-40725Medium
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Null pointer dereference in mod_proxy in Apache HTTP Server 2.4.59 and earlier allows an attacker to crash the server via a malicious request.
- CVE-2024-38475High
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- CVE-2023-38709Medium
Faulty input validation in the core of Apache HTTP Server through 2.4.58 allows malicious or exploitable backend/content generators to split HTTP responses, leading to HTTP response splitting attacks.
- CVE-2024-36387Medium
Serving WebSocket protocol upgrades over an HTTP/2 connection could result in a Null Pointer dereference, leading to a crash of the server process, degrading performance.
- CVE-2024-24795Medium
HTTP Response splitting in multiple modules in Apache HTTP Server allows an attacker that can inject malicious response headers into backend applications to cause an HTTP desynchronization attack.
Original NVD description (English source)
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.