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Highest advisory severityMedium 1 vendor · 1 advisory

CVE-2026-55990

CVE-2026-55990: 1 tracked advisory record across Red Hat. Compare source-reported impact, fixes and remediation.

Compare the source-linked records below. Ratings and product/version details belong to each advisory; they are not a single CVE-wide score or proof that every listed product is affected. How VulniPulse collects and checks evidence.

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Vendor advisory comparison

Red Hat

1 advisory
  • Advisory severityMedium5.9

    Medium [CVE-2026-55990] Denial of Service via faulty DNSCrypt configuration

    CVE-2026-55990Source published Source updated

    In NLnet Labs Unbound 1.7.0 up to and including 1.25.1, when the 'dnscrypt:' clause lists more 'dnscrypt-provider-cert:' files than there are matching 'dnscrypt-secret-key:' files, Unbound fills only the matched prefix and leaves the tail slots at the '0xdb' fill that libsodium's allocator writes into every allocation. Unbound would then iterate over the number of cert files, not the actual slots, so it walks into a slot with garbage data filled with '0xdb' bytes. Any unauthenticated client that sends one UDP datagram of ≥ 68 bytes whose first 8 bytes are '0xdb' to 'dnscrypt-port' will use that garbage entry which leads to a garbage dereference killing the server. This is a silent faulty configuration that goes unnoticed until triggered with the right client query. Unbound needs to be…

    Affected products in this advisory
    • Red Hat Hardened Images
    • Red Hat Enterprise Linux 10
    • Red Hat Enterprise Linux 8
    • Red Hat Enterprise Linux 9

    2 more entries in the full advisory.

    Source-reported affected versions
    • 1.7.0
    • 1.25.1
    Source-reported fixed versions
    • unbound-main-1.25.2-0.1.hum1
    • RHSA-2026:43588
    Mitigation guidance
    • To mitigate this issue, ensure that Unbound is not compiled with DNSCrypt support if the feature is not required. If DNSCrypt support is enabled, verify that the number of 'dnscrypt-provider-cert:' files precisely matches the number of 'dnscrypt-secret-key:' files in the Unbound configuration to prevent the faulty configuration that leads to a denial of service. Restart the Unbound service after any configuration changes.
    Full advisory and evidenceOpen source bulletin

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