An update for unbound is now available for openEuler-24.03-LTS-SP1 Security Advisory openeuler-security@openeuler.org openEuler security committee openEuler-SA-2026-2607 Final 1.0 1.0 2026-06-05 Initial 2026-06-05 2026-06-05 openEuler SA Tool V1.0 2026-06-05 unbound security update An update for unbound is now available for openEuler-24.03-LTS-SP1 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): NLnet Labs Unbound 1.6.2 up to and including version 1.25.0 has a denial of service vulnerability when compiled with DNSCrypt support ('--enable-dnscrypt'). A bad DNSCrypt query could underflow Unbound's DNSCrypt packet reading procedure that may lead to heap overflow. A malicious actor can exploit the vulnerability with a single bad DNSCrypt query that its decrypted plaintext consists entirely of '0x00' bytes and does not contain the expected '0x80' marker. Unbound would then start reading more bytes than necessary until it finds a non-'0x00' byte. Based on the underlying memory allocator and the memory layout, it could lead to heap overflow while reading followed by a crash. Likelihood of a crash is low, since it relies heavily on the underlying memory allocator and the memory layout. If the heap overflow does not happen, Unbound's later packet checks will deny the packet. Unbound 1.25.1 contains a patch with a fix to bound reading in the given buffer space.(CVE-2026-32792) NLnet Labs Unbound 1.16.2 up to and including version 1.25.0 has a vulnerability of the 'ghost domain names' family of attacks that could extend the ghost domain window by up to one cached TTL configured value. Similar to other 'ghost domain names' attacks, an adversary needs to control a (ghost) zone and be able to query a vulnerable Unbound. A single client NS query can cause Unbound to overwrite the cached expired parent-side referral NS rrset with the child-side apex NS rrset and essentially extend the ghost domain window by up to one cached TTL configured value ('cache-max-ttl'). In configurations where 'harden-referral-path: yes' is used (non-default configuration), no client NS query is required since Unbound implicitly performs that query. Unbound 1.25.1 contains a patch with a fix that does not allow extension of TTLs for (parent) NS records regardless of their trust.(CVE-2026-40622) NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability in the jostle logic that could defeat its purpose and degrade resolution performance. Retransmits of the same query could renew the age of slow running queries and not allow the jostle logic to see them as aged and potential targets for replacement with new queries. An adversary who can query a vulnerable Unbound and who can control a domain name server that replies slowly and/or maliciously to Unbound's queries can exploit the vulnerability and degrade the resolution performance of Unbound. When Unbound's 'num-queries-per-thread' reaches its limit, the jostle logic kicks in. When a new query comes in, half of the available queries that are also slow to resolve are candidates for replacement. The vulnerability then happens because duplicate queries that need resolution would skew the aging result by using the timestamp of the latest duplicate query instead of the original one that started the resolution effort. Cache and local data response performance remains unaffected. Coordinated attacks could raise this to a denial of resolution service. Unbound 1.25.1 contains a patch with a fix to attach an initial, non-updatable start time for incoming queries that allow the jostle logic to work as intended.(CVE-2026-42534) NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability in the DNSSEC validator where the code path to consult the negative cache for DS records does not take into account the limit on NSEC3 hash calculations introduced in 1.19.1. This leads to degradation of service during the attack. An adversary that controls a DNSSEC signed zone can exploit this by signing NSEC3 records with acceptably high iterations for child delegations and querying a vulnerable Unbound. Unbound will keep performing the allowed hash calculations on the NSEC3 records and will not limit the work by the mitigation introduced in 1.19.1. As a side effect, a global lock for the negative cache will be held for the duration of the hashing, blocking other threads that need to consult the negative cache. Coordinated attacks could raise the vulnerability to denial of service. Unbound 1.25.1 contains a patch with a fix to bound the vulnerable code path with the existing limit for NSEC3 hash calculations.(CVE-2026-42923) NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability when handling replies with very large RRsets that Unbound needs to perform name compression for. Malicious upstream responses with very large RRsets with records that don't share a suffix above the root can cause Unbound to spend a considerable time applying name compression to downstream replies. This can lead to degraded performance and eventually denial of service in well orchestrated attacks. An adversary can exploit the vulnerability by querying Unbound for the specially crafted contents of a malicious zone with very large RRsets. Before Unbound replies to the query it will try to apply name compression which was an unbounded operation that could lock the CPU until the whole packet was complete. A compression limit was introduced in 1.21.1 for this but it didn't account for the case where records would not share any suffix above the root. That causes Unbound to go in a different code path because of the compression tree lookup failure and eventually not increment the compression counter for those operations. Unbound 1.25.1 contains a patch with a fix that increments the compression counter regardless of the compression tree lookup. This is a complement fix to CVE-2024-8508.(CVE-2026-44390) NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a locking inconsistency vulnerability that when certain conditions are met (multi-threaded, RPZ XFR reload, RPZ zone with 'rpz-nsip'/'rpz-nsdname' triggers) it could result in heap use-after-free and eventual crash. An adversary can exploit the vulnerability if conditions are first met on a vulnerable Unbound, i.e., multi-threaded, an RPZ zone with 'rpz-nsip'/'rpz-nsdname' triggers and an ongoing XFR for that RPZ zone. Local RPZ files do not trigger the vulnerability. If the timing is right and an XFR happens at the same time another thread needs to read that RPZ zone, the reader may not hold the lock long enough and the thread applying the XFR may free objects that the reader is about to walk causing the use-after-free. Unbound 1.25.1 contains a patch with a fix to the locking code.(CVE-2026-44608) An update for unbound is now available for openEuler-24.03-LTS-SP1. openEuler Security has rated this update as having a security impact of high. A Common Vunlnerability Scoring System(CVSS)base score,which gives a detailed severity rating, is available for each vulnerability from the CVElink(s) in the References section. High unbound https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2607 https://www.openeuler.org/en/security/cve/detail/?cveId=CVE-2026-32792 https://www.openeuler.org/en/security/cve/detail/?cveId=CVE-2026-40622 https://www.openeuler.org/en/security/cve/detail/?cveId=CVE-2026-42534 https://www.openeuler.org/en/security/cve/detail/?cveId=CVE-2026-42923 https://www.openeuler.org/en/security/cve/detail/?cveId=CVE-2026-44390 https://www.openeuler.org/en/security/cve/detail/?cveId=CVE-2026-44608 https://nvd.nist.gov/vuln/detail/CVE-2026-32792 https://nvd.nist.gov/vuln/detail/CVE-2026-40622 https://nvd.nist.gov/vuln/detail/CVE-2026-42534 https://nvd.nist.gov/vuln/detail/CVE-2026-42923 https://nvd.nist.gov/vuln/detail/CVE-2026-44390 https://nvd.nist.gov/vuln/detail/CVE-2026-44608 openEuler-24.03-LTS-SP1 python3-unbound-1.17.1-17.oe2403sp1.aarch64.rpm unbound-1.17.1-17.oe2403sp1.aarch64.rpm unbound-anchor-1.17.1-17.oe2403sp1.aarch64.rpm unbound-debuginfo-1.17.1-17.oe2403sp1.aarch64.rpm unbound-debugsource-1.17.1-17.oe2403sp1.aarch64.rpm unbound-devel-1.17.1-17.oe2403sp1.aarch64.rpm unbound-help-1.17.1-17.oe2403sp1.aarch64.rpm unbound-libs-1.17.1-17.oe2403sp1.aarch64.rpm unbound-utils-1.17.1-17.oe2403sp1.aarch64.rpm python3-unbound-1.17.1-17.oe2403sp1.x86_64.rpm unbound-1.17.1-17.oe2403sp1.x86_64.rpm unbound-anchor-1.17.1-17.oe2403sp1.x86_64.rpm unbound-debuginfo-1.17.1-17.oe2403sp1.x86_64.rpm unbound-debugsource-1.17.1-17.oe2403sp1.x86_64.rpm unbound-devel-1.17.1-17.oe2403sp1.x86_64.rpm unbound-help-1.17.1-17.oe2403sp1.x86_64.rpm unbound-libs-1.17.1-17.oe2403sp1.x86_64.rpm unbound-utils-1.17.1-17.oe2403sp1.x86_64.rpm unbound-1.17.1-17.oe2403sp1.src.rpm NLnet Labs Unbound 1.6.2 up to and including version 1.25.0 has a denial of service vulnerability when compiled with DNSCrypt support ('--enable-dnscrypt'). A bad DNSCrypt query could underflow Unbound's DNSCrypt packet reading procedure that may lead to heap overflow. A malicious actor can exploit the vulnerability with a single bad DNSCrypt query that its decrypted plaintext consists entirely of '0x00' bytes and does not contain the expected '0x80' marker. Unbound would then start reading more bytes than necessary until it finds a non-'0x00' byte. Based on the underlying memory allocator and the memory layout, it could lead to heap overflow while reading followed by a crash. Likelihood of a crash is low, since it relies heavily on the underlying memory allocator and the memory layout. If the heap overflow does not happen, Unbound's later packet checks will deny the packet. Unbound 1.25.1 contains a patch with a fix to bound reading in the given buffer space. 2026-06-05 CVE-2026-32792 openEuler-24.03-LTS-SP1 Medium 5.3 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L unbound security update 2026-06-05 https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2607 NLnet Labs Unbound 1.16.2 up to and including version 1.25.0 has a vulnerability of the 'ghost domain names' family of attacks that could extend the ghost domain window by up to one cached TTL configured value. Similar to other 'ghost domain names' attacks, an adversary needs to control a (ghost) zone and be able to query a vulnerable Unbound. A single client NS query can cause Unbound to overwrite the cached expired parent-side referral NS rrset with the child-side apex NS rrset and essentially extend the ghost domain window by up to one cached TTL configured value ('cache-max-ttl'). In configurations where 'harden-referral-path: yes' is used (non-default configuration), no client NS query is required since Unbound implicitly performs that query. Unbound 1.25.1 contains a patch with a fix that does not allow extension of TTLs for (parent) NS records regardless of their trust. 2026-06-05 CVE-2026-40622 openEuler-24.03-LTS-SP1 High 7.5 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N unbound security update 2026-06-05 https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2607 NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability in the jostle logic that could defeat its purpose and degrade resolution performance. Retransmits of the same query could renew the age of slow running queries and not allow the jostle logic to see them as aged and potential targets for replacement with new queries. An adversary who can query a vulnerable Unbound and who can control a domain name server that replies slowly and/or maliciously to Unbound's queries can exploit the vulnerability and degrade the resolution performance of Unbound. When Unbound's 'num-queries-per-thread' reaches its limit, the jostle logic kicks in. When a new query comes in, half of the available queries that are also slow to resolve are candidates for replacement. The vulnerability then happens because duplicate queries that need resolution would skew the aging result by using the timestamp of the latest duplicate query instead of the original one that started the resolution effort. Cache and local data response performance remains unaffected. Coordinated attacks could raise this to a denial of resolution service. Unbound 1.25.1 contains a patch with a fix to attach an initial, non-updatable start time for incoming queries that allow the jostle logic to work as intended. 2026-06-05 CVE-2026-42534 openEuler-24.03-LTS-SP1 Medium 5.3 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L unbound security update 2026-06-05 https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2607 NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability in the DNSSEC validator where the code path to consult the negative cache for DS records does not take into account the limit on NSEC3 hash calculations introduced in 1.19.1. This leads to degradation of service during the attack. An adversary that controls a DNSSEC signed zone can exploit this by signing NSEC3 records with acceptably high iterations for child delegations and querying a vulnerable Unbound. Unbound will keep performing the allowed hash calculations on the NSEC3 records and will not limit the work by the mitigation introduced in 1.19.1. As a side effect, a global lock for the negative cache will be held for the duration of the hashing, blocking other threads that need to consult the negative cache. Coordinated attacks could raise the vulnerability to denial of service. Unbound 1.25.1 contains a patch with a fix to bound the vulnerable code path with the existing limit for NSEC3 hash calculations. 2026-06-05 CVE-2026-42923 openEuler-24.03-LTS-SP1 Medium 5.3 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L unbound security update 2026-06-05 https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2607 NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability when handling replies with very large RRsets that Unbound needs to perform name compression for. Malicious upstream responses with very large RRsets with records that don't share a suffix above the root can cause Unbound to spend a considerable time applying name compression to downstream replies. This can lead to degraded performance and eventually denial of service in well orchestrated attacks. An adversary can exploit the vulnerability by querying Unbound for the specially crafted contents of a malicious zone with very large RRsets. Before Unbound replies to the query it will try to apply name compression which was an unbounded operation that could lock the CPU until the whole packet was complete. A compression limit was introduced in 1.21.1 for this but it didn't account for the case where records would not share any suffix above the root. That causes Unbound to go in a different code path because of the compression tree lookup failure and eventually not increment the compression counter for those operations. Unbound 1.25.1 contains a patch with a fix that increments the compression counter regardless of the compression tree lookup. This is a complement fix to CVE-2024-8508. 2026-06-05 CVE-2026-44390 openEuler-24.03-LTS-SP1 Medium 5.3 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L unbound security update 2026-06-05 https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2607 NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a locking inconsistency vulnerability that when certain conditions are met (multi-threaded, RPZ XFR reload, RPZ zone with 'rpz-nsip'/'rpz-nsdname' triggers) it could result in heap use-after-free and eventual crash. An adversary can exploit the vulnerability if conditions are first met on a vulnerable Unbound, i.e., multi-threaded, an RPZ zone with 'rpz-nsip'/'rpz-nsdname' triggers and an ongoing XFR for that RPZ zone. Local RPZ files do not trigger the vulnerability. If the timing is right and an XFR happens at the same time another thread needs to read that RPZ zone, the reader may not hold the lock long enough and the thread applying the XFR may free objects that the reader is about to walk causing the use-after-free. Unbound 1.25.1 contains a patch with a fix to the locking code. 2026-06-05 CVE-2026-44608 openEuler-24.03-LTS-SP1 Medium 5.9 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H unbound security update 2026-06-05 https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2607