Hickory DNS hickory-recursor 0.1 through 0.25.2 allows cross-zone poisoning because cached data is not directly associated with a query that triggered a response.

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Hickory DNS hickory-recursor 0.1 through 0.25.2 allows cross-zone poisoning because cached data is not directly associated with a query that triggered a response.

Source published

26 Apr 2026 02:38:41 UTC

Source modified

27 Apr 2026 13:33:50 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 4.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N

Hickory DNS hickory-recursor 0.1 through 0.25.2 allows cross-zone poisoning because cached data is not directly associated with a query that triggered a response.

Source published

Apr 26, 2026, 2:38:41 AM (timezone not stated)

Source modified

Apr 27, 2026, 1:33:50 PM (timezone not stated)

Observed here

1 Nov 2026 07:12:36 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 4.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N

Hickory DNS hickory-recursor 0.1 through 0.25.2 allows cross-zone poisoning because cached data is not directly associated with a query that triggered a response.

Source published

26 Apr 2026 03:15:59 UTC

Source modified

26 Oct 2026 22:10:00 UTC

Observed here

27 Oct 2026 11:12:01 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 4.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N

# Summary The Hickory DNS project's experimental `hickory-recursor` crate's record cache (`DnsLru`) stores records from DNS responses keyed by each record's own (name, type), not by the query that triggered the response. `cache_response()` in `crates/recursor/src/lib.rs` chains `ANSWER`, `AUTHORITY`, and `ADDITIONAL` sections into one record iterator before insertion. The bailiwick filter it applies uses the zone context of the NS pool that serviced the lookup, not the zone being queried. This creates a cross-zone poisoning path. When Hickory builds the NS pool for `attacker.poc.` it uses the parent `poc.` `NS` pool (`ns.zone() = "poc."`). If the `poc.` nameserver under the attacker's control includes in its response's `AUTHORITY` section a record for a sibling zone like `victim.poc. NS ns.evil.poc.`, the bailiwick check `is_subzone("poc.", "victim.poc.")` passes (`victim.poc.` is a subdomain of `poc.`). The record is stored under `(victim.poc., NS)` in the shared cache. Subsequently, any client querying a name in `victim.poc`. causes Hickory to build its NS pool from the poisoned cache entry, routing queries to the attacker's nameserver (`ns.evil.poc.`) rather than to the legitimate nameserver for `victim.poc.`. The legitimate `NS` for that zone receives zero queries. This issue is fixed in `hickory-resolver` 0.26.0 with the `recursor` feature through an architectural change to response-level caching: responses are stored keyed by the originating query `(name, type)`. A response to `(attacker.poc. NS)` is stored only under that key and cannot affect the `(victim.poc., NS)` cache entry. Hickory DNS believes this issue has been present in all published versions of the experimental `hickory-recursor` crate, which has now been folded into the `hickory-resolver` crate under the non-default `recursor` feature flag. The `hickory-recursor` crate will not receive any updates going forward and all users should migrate to `hickory-resolver` with the `recursor` feature. Users of the `hickory-dns` binary configured with the opt-in `recursor` feature and a configuration acting as a recursive resolver should update to 0.26.0+. ### Reporter Qifan Zhang, Palo Alto Networks

Source published

30 Apr 2026 18:10:58 UTC

Source modified

8 Jul 2026 08:12:56 UTC

Observed here

24 Oct 2026 13:19:54 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Publisher rating · HIGH