CVE-2024-43167

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 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.

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 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.

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 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: guard against a NULL forward-zone name in ub_ctx_set_fwd to prevent a NULL pointer dereference
• CVE-2026-44690: reject RRSIG label counts below the signer label count and restrict wildcard rrset cache updates to the signer authority, deferring the cache write until the proof succeeds
• CVE-2026-56416: bound the second domain name in canonicalized RDATA and reject multi-dname RRs whose rdata ends early, preventing a heap buffer overflow

• CVE-2024-33655: add the upstream wait-limit and discard-timeout mechanism so accumulated recursion replies can no longer be released as a pulsing burst (DNSBomb), including every upstream follow-up to that mechanism: discard only UDP replies and never a reply on an open stream connection, clear the HTTP/2 stream back-pointer on the drop paths, account discarded replies in mesh num_reply_addrs, and fix CVE-2026-56444 in the serve-expired discard path
• CVE-2024-43167: NULL-check the first forward stub name in ub_ctx_set_fwd() to prevent a NULL pointer dereference in libunbound, and reject a forward-zone, stub-zone or view without a name at config parse time so no name-less object reaches the daemon
• CVE-2026-42955: clamp the cached TTL of parent-side A/AAAA glue as well as NS records so a client query can no longer renew a ghost domain delegation
• CVE-2026-46582: keep a secure wildcard RRset out of the rrset cache until the NSEC wildcard proof completes, preventing poisoning via the serve-expired reply path
• CVE-2026-50243: skip the response-ip/RPZ rewrite for BOGUS answers so a spoofed DNSSEC-protected answer is no longer redirected as INSECURE
• CVE-2026-55708: enter the default-protected local zones when unbound-control view_local_data creates a view-specific local zone tree

Along with various minor bug fixing, this update addresses the security vulnerability CVE-2024-43167.

These are all security issues fixed in the libunbound8-1.21.0-1.1 package on the GA media of openSUSE Tumbleweed.

This update for unbound fixes the following issues:

• CVE-2024-43167: Fix null pointer dereference issue in function ub_ctx_set_fwd (bsc#1229068)

This update for unbound fixes the following issues:

• CVE-2024-43167: Fix null pointer dereference issue in function ub_ctx_set_fwd (bsc#1229068)

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)