SB20260721114 - Ubuntu update for apache2
Published: July 21, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 15 vulnerabilities.
1) NULL pointer dereference (CVE-ID: CVE-2026-33007)
CWE-ID: CWE-476 - NULL Pointer Dereference
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to a NULL pointer dereference in mod_authn_socache when handling requests in a caching forward proxy configuration. A remote attacker can send a malicious request to cause a denial of service.
The issue crashes a child process only in a caching forward proxy configuration.
2) HTTP response splitting (CVE-ID: CVE-2026-33523)
CWE-ID: CWE-113 - Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response Splitting')
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
The vulnerability allows a remote attacker to manipulate HTTP responses.
The vulnerability exists due to improper neutralization of CRLF sequences in multiple Apache HTTP Server modules when forwarding a backend status line. A remote attacker can supply a malicious backend response to manipulate HTTP responses.
Exploitation requires an untrusted or compromised backend server.
3) Out-of-bounds read (CVE-ID: CVE-2026-33857)
CWE-ID: CWE-125 - Out-of-bounds read
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to an out-of-bounds read in mod_proxy_ajp AJP getter functions when parsing AJP data. A remote attacker can send a specially crafted AJP message to disclose sensitive information.
Exploitation requires Apache HTTP Server to connect to an untrusted or compromised AJP backend server.
4) Out-of-bounds read (CVE-ID: CVE-2026-34032)
CWE-ID: CWE-125 - Out-of-bounds read
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to improper null termination leading to an out-of-bounds read in mod_proxy_ajp ajp_msg_get_string when parsing AJP string data. A remote attacker can send a specially crafted AJP message to disclose sensitive information.
Exploitation requires Apache HTTP Server to connect to an untrusted or compromised AJP backend server.
5) Buffer overflow (CVE-ID: CVE-2026-34355)
CWE-ID: CWE-120 - Buffer overflow
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to buffer overflow in mod_proxy_html when processing content from an untrusted backend. A remote attacker can operate an untrusted backend to cause a denial of service.
6) Heap-based buffer overflow (CVE-ID: CVE-2026-34356)
CWE-ID: CWE-122 - Heap-based Buffer Overflow
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber
The vulnerability allows a remote attacker to execute arbitrary code.
The vulnerability exists due to heap-based buffer overflow in ProxyPassReverseCookie* processing when interacting with malicious backend servers. A remote attacker can operate a malicious backend server to execute arbitrary code.
7) Path traversal (CVE-ID: CVE-2026-42535)
CWE-ID: CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to improper path handling in mod_dav_fs when a WebDAV content author directly manipulates trusted DAV property databases. A remote user can manipulate trusted DAV property databases to cause a denial of service.
The issue may cause child process crashes.
8) Heap-based buffer overflow (CVE-ID: CVE-2026-42536)
CWE-ID: CWE-122 - Heap-based Buffer Overflow
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber
The vulnerability allows a remote attacker to execute arbitrary code.
The vulnerability exists due to heap-based buffer overflow in mod_xml2enc xml2StartParse when parsing untrusted content. A remote attacker can supply crafted content to execute arbitrary code.
9) Out-of-bounds read (CVE-ID: CVE-2026-43951)
CWE-ID: CWE-125 - Out-of-bounds read
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to out-of-bounds read in merge_response_headers when processing responses with mod_headers, mod_mime, and multiple response languages. A remote attacker can trigger processing of affected responses to cause a denial of service.
The issue occurs when mod_headers and mod_mime are used with multiple response languages.
10) Improper privilege management (CVE-ID: CVE-2026-44119)
CWE-ID: CWE-269 - Improper Privilege Management
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a local user to disclose sensitive information.
The vulnerability exists due to improper privilege management in expression handling in .htaccess across multiple modules when processing .htaccess expressions. A local user can author .htaccess expressions to disclose sensitive information.
The issue allows reading files with the privileges of the httpd user.
11) Out-of-bounds read (CVE-ID: CVE-2026-44185)
CWE-ID: CWE-125 - Out-of-bounds read
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to out-of-bounds read in mod_ssl OCSP send_request when sending outbound OCSP requests to an attacker-controlled OCSP server. A remote attacker can operate a malicious OCSP server to disclose sensitive information.
12) Infinite loop (CVE-ID: CVE-2026-44186)
CWE-ID: CWE-835 - Loop with Unreachable Exit Condition ('Infinite Loop')
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to an infinite loop in proxy_ftp_handler in mod_proxy_ftp when interacting with an attacker-controlled backend FTP server. A remote attacker can operate a malicious backend FTP server to cause a denial of service.
13) Out-of-bounds write (CVE-ID: CVE-2026-44631)
CWE-ID: CWE-787 - Out-of-bounds write
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to out-of-bounds write in ap_regname when processing crafted regular expressions in the configuration. A local user can place crafted regular expressions in the configuration to cause a denial of service.
14) Use-after-free (CVE-ID: CVE-2026-48913)
CWE-ID: CWE-416 - Use After Free
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber
The vulnerability allows a remote attacker to execute arbitrary code.
The vulnerability exists due to use-after-free in mod_http2 when file handles are already exhausted. A remote attacker can trigger request processing under file descriptor exhaustion conditions to execute arbitrary code.
Exploitation requires the server to have exhausted file handles.
15) Resource exhaustion (CVE-ID: CVE-2026-49975)
CWE-ID: CWE-400 - Resource exhaustion
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to uncontrolled resource consumption in the HTTP/2 request handling and HPACK header processing when handling crafted HTTP/2 requests that use repeated indexed header references and a stalled flow-control window. A remote attacker can send specially crafted HTTP/2 requests to cause a denial of service.
The issue is reachable in the default HTTP/2 configuration.
Remediation
Install update from vendor's website.