CVE-2024-43168

Unbound is a validating, recursive, caching DNS resolver. It is designed to be fast and lean and incorporates modern features based on open standards. To help increase online privacy, Unbound supports DNS-over-TLS which allows clients to encrypt their communication. Unbound is available for most platforms such as FreeBSD, OpenBSD, NetBSD, MacOS, Linux and Microsoft Windows. Unbound is a totally free, open source software under the BSD license. It doesn't make custom builds or provide specific features to paying customers only.

Security Fix(es):

A NULL pointer dereference flaw was found in the ub_ctx_set_fwd function in Unbound. This issue could allow an attacker who can invoke specific sequences of API calls to cause a segmentation fault. When certain API functions such as ub_ctx_set_fwd and ub_ctx_resolvconf are called in a particular order, the program attempts to read from a NULL pointer, leading to a crash. This issue can result in a denial of service by causing the application to terminate unexpectedly.(CVE-2024-43167)

A heap-buffer-overflow flaw was found in the cfg_mark_ports function within Unbound's config_file.c, which can lead to memory corruption. This issue could allow an attacker with local access to provide specially crafted input, potentially causing the application to crash or allowing arbitrary code execution. This could result in a denial of service or unauthorized actions on the system.(CVE-2024-43168)

DISPUTE NOTE: this issue does not pose a security risk as it (according to analysis by the original software developer, NLnet Labs) falls within the expected functionality and security controls of the application. Red Hat has made a claim that there is a security risk within Red Hat products. NLnet Labs has no further information about the claim, and suggests that affected Red Hat customers refer to available Red Hat documentation or support channels. ORIGINAL DESCRIPTION: A heap-buffer-overflow flaw was found in the cfg_mark_ports function within Unbound's config_file.c, which can lead to memory corruption. This issue could allow an attacker with local access to provide specially crafted input, potentially causing the application to crash or allowing arbitrary code execution. This could result in a denial of service or unauthorized actions on the system.

DISPUTE NOTE: this issue does not pose a security risk as it (according to analysis by the original software developer, NLnet Labs) falls within the expected functionality and security controls of the application. Red Hat has made a claim that there is a security risk within Red Hat products. NLnet Labs has no further information about the claim, and suggests that affected Red Hat customers refer to available Red Hat documentation or support channels. ORIGINAL DESCRIPTION: A heap-buffer-overflow flaw was found in the cfg_mark_ports function within Unbound's config_file.c, which can lead to memory corruption. This issue could allow an attacker with local access to provide specially crafted input, potentially causing the application to crash or allowing arbitrary code execution. This could result in a denial of service or unauthorized actions on the system.

DISPUTE NOTE: this issue does not pose a security risk as it (according to analysis by the original software developer, NLnet Labs) falls within the expected functionality and security controls of the application. Red Hat has made a claim that there is a security risk within Red Hat products. NLnet Labs has no further information about the claim, and suggests that affected Red Hat customers refer to available Red Hat documentation or support channels. ORIGINAL DESCRIPTION: A heap-buffer-overflow flaw was found in the cfg_mark_ports function within Unbound's config_file.c, which can lead to memory corruption. This issue could allow an attacker with local access to provide specially crafted input, potentially causing the application to crash or allowing arbitrary code execution. This could result in a denial of service or unauthorized actions on the system.

• CVE-2026-42923: cap NSEC3 hash calculations in the negative-cache DS proof and reject oversized NSEC3 salt
• CVE-2024-43168: reject negative port numbers in outgoing-port-permit/avoid to prevent an out-of-bounds write

• CVE-2026-50243: do not let response-ip/rpz rewrite a BOGUS answer; return SERVFAIL
• CVE-2026-42923: cap NSEC3 hash calculations in the negative-cache DS proof and reject oversized NSEC3 salt
• CVE-2024-43168: reject negative port numbers in outgoing-port-permit/avoid to prevent an out-of-bounds write

• CVE-2026-50243: do not let response-ip/rpz rewrite a BOGUS answer; return SERVFAIL
• CVE-2026-42923: cap NSEC3 hash calculations in the negative-cache DS proof and reject oversized NSEC3 salt
• CVE-2024-43168: reject negative port numbers in outgoing-port-permit/avoid to prevent an out-of-bounds write

It was discovered that Unbound incorrectly handled string comparisons, which could lead to a NULL pointer dereference. An attacker could potentially use this issue to cause a denial of service. (CVE-2024-43167)

It was discovered that Unbound incorrectly handled memory in cfg_mark_ports, which could lead to a heap buffer overflow. A local attacker could potentially use this issue to cause a denial of service or execute arbitrary code. (CVE-2024-43168)