CVE-2025-11411 | THREATINT

Description

NLnet Labs Unbound up to and including version 1.24.1 is vulnerable to possible domain hijack attacks. Promiscuous NS RRSets that complement positive DNS replies in the authority section can be used to trick resolvers to update their delegation information for the zone. Usually these RRSets are used to update the resolver's knowledge of the zone's name servers. A malicious actor can exploit the possible poisonous effect by injecting NS RRSets (and possibly their respective address records) in a reply. This could be done for example by trying to spoof a packet or fragmentation attacks. Unbound would then proceed to update the NS RRSet data it already has since the new data has enough trust for it, i.e., in-zone data for the delegation point. Unbound 1.24.1 includes a fix that scrubs unsolicited NS RRSets (and their respective address records) from replies mitigating the possible poison effect. Unbound 1.24.2 includes an additional fix that scrubs unsolicited NS RRSets (and their respective address records) from YXDOMAIN and non-referral nodata replies, further mitigating the possible poison effect.

PUBLISHED Reserved 2025-10-07 | Published 2025-10-22 | Updated 2025-12-05 | Assigner NLnet Labs

MEDIUM: 5.7CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:H/E:P

Problem types

CWE-349 Acceptance of Extraneous Untrusted Data With Trusted Data

Product status

Default status

unaffected

Any version

affected

Timeline

2025-07-09:	Issue reported by Yuxiao Wu
2025-08-12:	Issue acknowledged and mitigation shared by NLnet Labs
2025-10-22:	Fixes released with Unbound 1.24.1 (coordinated with other vendors)
2025-11-07:	Not complete fix in Unbound 1.24.1 reported by TaoFei Guo
2025-11-07:	Issue acknowledged and mitigation shared by NLnet Labs
2025-11-07:	Mitigation acknowledged by TaoFei Guo
2025-11-26:	Additional fixes released with Unbound 1.24.2

Credits

Yuxiao Wu (Tsinghua University) finder

Yunyi Zhang (Tsinghua University) finder

Baojun Liu (Tsinghua University) finder

Haixin Duan (Tsinghua University) finder

TaoFei Guo (Peking University) finder

Yang Luo (Tsinghua University) finder

JianJun Chen (Tsinghua University) finder

References

lists.debian.org/debian-lts-announce/2025/11/msg00008.html

www.openwall.com/lists/oss-security/2025/11/26/4

lists.debian.org/debian-lts-announce/2025/11/msg00032.html

www.nlnetlabs.nl/downloads/unbound/CVE-2025-11411.txt vendor-advisory

cve.org (CVE-2025-11411)

nvd.nist.gov (CVE-2025-11411)

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