94 results · Feed
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Medium 6.5
Apache HTTP Server: multiple modules: HTTP response splitting forwarding malicious status line
HTTP response splitting vulnerability in multiple Apache HTTP Server modules with untrusted or compromised backend servers. This issue affects Apache HTTP Server: from through 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.
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Medium 5.3
Apache HTTP Server: Off-by-one OOB reads in AJP getter functions
Out-of-bounds Read vulnerability in mod_proxy_ajp of Apache HTTP Server. This issue affects Apache HTTP Server: through 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.
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Medium 5.3
Apache HTTP Server: mod_proxy_ajp: Heap Buffer Over-Read Due to Missing Null-Termination Check (ajp_msg_get_string)
Improper Null Termination, Out-of-bounds Read vulnerability in Apache HTTP Server. This issue affects Apache HTTP Server: through 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.
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High 7.5
Apache HTTP Server: mod_proxy_ajp: Heap Over-Read and memory disclosure in ajp_parse_data()
Buffer Over-read vulnerability in Apache HTTP Server. This issue affects Apache HTTP Server: through 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.
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High 8.8CVE-2026-24072 Public exploit
Apache HTTP Server: mod_rewrite elevation of privileges via ap_expr
An escalation of privilege bug in various modules in Apache HTTP 2.4.66 and earlier allows local .htaccess authors to read files with the privileges of the httpd user. Users are recommended to upgrade to version 2.4.67, which fixes this issue.
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High 8.3CVE-2025-58098 Public exploit
Apache HTTP Server: Server Side Includes adds query string to #exec cmd=...
Apache HTTP Server 2.4.65 and earlier with Server Side Includes (SSI) enabled and mod_cgid (but not mod_cgi) passes the shell-escaped query string to #exec cmd="..." directives. This issue affects Apache HTTP Server before 2.4.66. Users are recommended to upg…
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Medium 5.4
Apache HTTP Server: mod_userdir+suexec bypass via AllowOverride FileInfo
mod_userdir+suexec bypass via AllowOverride FileInfo vulnerability in Apache HTTP Server. Users with access to use the RequestHeader directive in htaccess can cause some CGI scripts to run under an unexpected userid. This issue affects Apache HTTP Server: fro…
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Medium 6.5
Apache HTTP Server: CGI environment variable override
Improper Neutralization of Escape, Meta, or Control Sequences vulnerability in Apache HTTP Server through environment variables set via the Apache configuration unexpectedly superseding variables calculated by the server for CGI programs. This issue affects A…
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High 7.5
Apache HTTP Server: mod_md (ACME), unintended retry intervals
An integer overflow in the case of failed ACME certificate renewal leads, after a number of failures (~30 days in default configurations), to the backoff timer becoming 0. Attempts to renew the certificate then are repeated without delays until it succeeds. T…
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Medium 6.3
Apache HTTP Server: 'RewriteCond expr' always evaluates to true in 2.4.64
A bug in Apache HTTP Server 2.4.64 results in all "RewriteCond expr ..." tests evaluating as "true". Users are recommended to upgrade to version 2.4.65, which fixes the issue.
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High 7.5CVE-2025-53020 Public exploit
Apache HTTP Server: HTTP/2 DoS by Memory Increase
Late Release of Memory after Effective Lifetime vulnerability in Apache HTTP Server. This issue affects Apache HTTP Server: from 2.4.17 up to 2.4.63. Users are recommended to upgrade to version 2.4.64, which fixes the issue.
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High 7.4CVE-2025-49812 Public exploit
Apache HTTP Server: mod_ssl TLS upgrade attack
In some mod_ssl configurations on Apache HTTP Server versions through to 2.4.63, an HTTP desynchronisation attack allows a man-in-the-middle attacker to hijack an HTTP session via a TLS upgrade. Only configurations using "SSLEngine optional" to enable TLS upg…
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High 7.5
Apache HTTP Server: mod_proxy_http2 denial of service
In certain proxy configurations, a denial of service attack against Apache HTTP Server versions 2.4.26 through to 2.4.63 can be triggered by untrusted clients causing an assertion in mod_proxy_http2. Configurations affected are a reverse proxy is configured f…
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Critical 9.1CVE-2025-23048 Public exploit
Apache HTTP Server: mod_ssl access control bypass with session resumption
In some mod_ssl configurations on Apache HTTP Server 2.4.35 through to 2.4.63, an access control bypass by trusted clients is possible using TLS 1.3 session resumption. Configurations are affected when mod_ssl is configured for multiple virtual hosts, with ea…
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High 7.5
Apache HTTP Server: mod_ssl error log variable escaping
Insufficient escaping of user-supplied data in mod_ssl in Apache HTTP Server 2.4.63 and earlier allows an untrusted SSL/TLS client to insert escape characters into log files in some configurations. In a logging configuration where CustomLog is used with "%{va…
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High 7.5
Apache HTTP Server: SSRF with mod_headers setting Content-Type header
SSRF in Apache HTTP Server with mod_proxy loaded allows an attacker to send outbound proxy requests to a URL controlled by the attacker. Requires an unlikely configuration where mod_headers is configured to modify the Content-Type request or response header …
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High 7.5
Apache HTTP Server: HTTP response splitting
HTTP response splitting in the core of Apache HTTP Server allows an attacker who can manipulate the Content-Type response headers of applications hosted or proxied by the server can split the HTTP response. This vulnerability was described as CVE-2023-38709 b…
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Medium 5.3CVE-2024-40725 Public exploit
Apache HTTP Server: source code disclosure with handlers configured via AddType
A partial fix for CVE-2024-39884 in the core of Apache HTTP Server 2.4.61 ignores some use of the legacy content-type based configuration of handlers. "AddType" and similar configuration, under some circumstances where files are requested indirectly, result …
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Medium 6.2
Apache HTTP Server: source code disclosure with handlers configured via AddType
A regression in the core of Apache HTTP Server 2.4.60 ignores some use of the legacy content-type based configuration of handlers. "AddType" and similar configuration, under some circumstances where files are requested indirectly, result in source code disc…
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High 8.1
Apache HTTP Server proxy encoding problem
Encoding problem in mod_proxy in Apache HTTP Server 2.4.59 and earlier allows request URLs with incorrect encoding to be sent to backend services, potentially bypassing authentication via crafted requests. Users are recommended to upgrade to version 2.4.60, w…
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Medium 5.4
Apache HTTP Server: DoS by Null pointer in websocket over HTTP/2
Serving WebSocket protocol upgrades over a HTTP/2 connection could result in a Null Pointer dereference, leading to a crash of the server process, degrading performance.
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High 7.5
Apache HTTP Server: HTTP/2 DoS by memory exhaustion on endless continuation frames
HTTP/2 incoming headers exceeding the limit are temporarily buffered in nghttp2 in order to generate an informative HTTP 413 response. If a client does not stop sending headers, this leads to memory exhaustion.
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Medium 6.3
Apache HTTP Server: HTTP Response Splitting in multiple modules
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. Users are recommended to upgrade to version 2.4.59, which fixe…
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High 7.3CVE-2023-38709 Public exploit
Apache HTTP Server: HTTP response splitting
Faulty input validation in the core of Apache allows malicious or exploitable backend/content generators to split HTTP responses. This issue affects Apache HTTP Server: through 2.4.58.
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Unscored —
Apache HTTP Server: DoS in HTTP/2 with initial windows size 0
An attacker, opening a HTTP/2 connection with an initial window size of 0, was able to block handling of that connection indefinitely in Apache HTTP Server. This could be used to exhaust worker resources in the server, similar to the well known "slow loris" a…
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Unscored —CVE-2023-45802 Public exploit
Apache HTTP Server: HTTP/2 stream memory not reclaimed right away on RST
When a HTTP/2 stream was reset (RST frame) by a client, there was a time window were the request's memory resources were not reclaimed immediately. Instead, de-allocation was deferred to connection close. A client could send new requests and resets, keeping t…
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High 7.5
HTTP/2 Stream Cancellation Attack
The HTTP/2 protocol allows a denial of service (server resource consumption) because request cancellation can reset many streams quickly, as exploited in the wild in August through October 2023.
KEV Oct 10, 2023 -
High 7.5
Apache HTTP Server: mod_proxy_uwsgi HTTP response splitting
HTTP Response Smuggling vulnerability in Apache HTTP Server via mod_proxy_uwsgi. This issue affects Apache HTTP Server: from 2.4.30 through 2.4.55. Special characters in the origin response header can truncate/split the response forwarded to the client.
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Critical 9.8
Apache HTTP Server: HTTP request splitting with mod_rewrite and mod_proxy
Some mod_proxy configurations on Apache HTTP Server versions 2.4.0 through 2.4.55 allow a HTTP Request Smuggling attack. Configurations are affected when mod_proxy is enabled along with some form of RewriteRule or ProxyPassMatch in which a non-specific patter…
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Medium 5.3CVE-2022-37436 EPSS 53%
Apache HTTP Server: mod_proxy prior to 2.4.55 allows a backend to trigger HTTP response splitting
Prior to Apache HTTP Server 2.4.55, a malicious backend can cause the response headers to be truncated early, resulting in some headers being incorporated into the response body. If the later headers have any security purpose, they will not be interpreted by …
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Critical 9.0
Apache HTTP Server: mod_proxy_ajp Possible request smuggling
Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling') vulnerability in mod_proxy_ajp of Apache HTTP Server allows an attacker to smuggle requests to the AJP server it forwards requests to. This issue affects Apache HTTP Server Apache HTTP Se…
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Unscored —
mod_sed: Read/write beyond bounds
Out-of-bounds Write vulnerability in mod_sed of Apache HTTP Server allows an attacker to overwrite heap memory with possibly attacker provided data. This issue affects Apache HTTP Server 2.4 version 2.4.52 and prior versions.
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Unscored —CVE-2022-22721 EPSS 42%
core: Possible buffer overflow with very large or unlimited LimitXMLRequestBody
If LimitXMLRequestBody is set to allow request bodies larger than 350MB (defaults to 1M) on 32 bit systems an integer overflow happens which later causes out of bounds writes. This issue affects Apache HTTP Server 2.4.52 and earlier.
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Unscored —
HTTP request smuggling vulnerability in Apache HTTP Server 2.4.52 and earlier
Apache HTTP Server 2.4.52 and earlier fails to close inbound connection when errors are encountered discarding the request body, exposing the server to HTTP Request Smuggling
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Unscored —CVE-2022-22719 EPSS 70%
mod_lua Use of uninitialized value of in r:parsebody
A carefully crafted request body can cause a read to a random memory area which could cause the process to crash. This issue affects Apache HTTP Server 2.4.52 and earlier.
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Unscored —CVE-2021-44224 EPSS 82%
Possible NULL dereference or SSRF in forward proxy configurations in Apache HTTP Server 2.4.51 and earlier
A crafted URI sent to httpd configured as a forward proxy (ProxyRequests on) can cause a crash (NULL pointer dereference) or, for configurations mixing forward and reverse proxy declarations, can allow for requests to be directed to a declared Unix Domain Soc…
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Unscored —
Possible buffer overflow when parsing multipart content in mod_lua of Apache HTTP Server 2.4.51 and earlier
A carefully crafted request body can cause a buffer overflow in the mod_lua multipart parser (r:parsebody() called from Lua scripts). The Apache httpd team is not aware of an exploit for the vulnerabilty though it might be possible to craft one. This issue af…
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Critical 9.0
mod_proxy SSRF
A crafted request uri-path can cause mod_proxy to forward the request to an origin server choosen by the remote user. This issue affects Apache HTTP Server 2.4.48 and earlier.
KEV Dec 1, 2021 -
Unscored —CVE-2021-39275 EPSS 39%
ap_escape_quotes buffer overflow
ap_escape_quotes() may write beyond the end of a buffer when given malicious input. No included modules pass untrusted data to these functions, but third-party / external modules may. This issue affects Apache HTTP Server 2.4.48 and earlier.
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Unscored —CVE-2021-36160 EPSS 64%
mod_proxy_uwsgi out of bound read
A carefully crafted request uri-path can cause mod_proxy_uwsgi to read above the allocated memory and crash (DoS). This issue affects Apache HTTP Server versions 2.4.30 to 2.4.48 (inclusive).