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CVE Record

CVE-2026-41292: Long list of incoming EDNS options degrades performance

NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to a degradation of service attack related to parsing long lists of incoming EDNS options. An adversary sending queries with too many EDNS options can hold Unbound threads hostage while they are parsing and creating internal data structures for the options. Coordinated attacks can result in degradation and/or denial of service. Unbound 1.25.1 contains a patch with a fix to limit acceptable incoming EDNS options (100).

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

Unbound can spend excessive processing time handling DNS queries containing unusually long lists of EDNS options. Repeated malicious queries may occupy resolver threads, slow DNS responses, and potentially cause denial of service. The issue affects Unbound through version 1.25.0; version 1.25.1 limits incoming EDNS options to 100.

Executive priority

Treat as a high-priority availability risk for externally reachable or business-critical DNS resolvers. DNS disruption can affect many dependent services even without data theft. Accelerate patching where query access is broad; schedule prompt remediation elsewhere after confirming exposure and resilience controls.

Technical view

CVE-2026-41292 is an unauthenticated, network-reachable resource-consumption flaw in Unbound’s EDNS option parsing. Excessive options cause threads to remain busy parsing input and creating internal data structures. Coordinated requests can exhaust processing capacity. CVSS 3.1 is 7.5: availability impact is high, with no confidentiality or integrity impact identified.

Likely exposure

Exposure is highest where Unbound through 1.25.0 accepts DNS queries from untrusted or broadly reachable clients. Internal-only resolvers may have reduced reachability but remain exposed to compromised or unauthorized internal clients. The supplied affected-product metadata is inconsistent, so version verification against the vendor advisory is important.

Exploitation context

The attack requires no privileges or user interaction and can be performed remotely by sending crafted DNS queries. However, the source bundle marks this CVE as absent from KEV and provides no evidence of active exploitation. Public exploit availability is not established by the supplied sources.

Researcher notes

The weakness aligns with asymmetric resource consumption and insufficient input limits, referenced as CWE-1050, CWE-407, and CWE-770. The vendor fix imposes a maximum of 100 incoming EDNS options. The bundle does not establish attack traffic volume, practical amplification, active exploitation, or public proof-of-concept availability.

Mitigation direction

  • Upgrade NLnet Labs Unbound to version 1.25.1 or a vendor package containing the corresponding fix.
  • Prioritize internet-facing and broadly accessible resolvers for remediation.
  • Restrict DNS query access to intended clients where operationally feasible.
  • Review applicable Red Hat advisories when Unbound is supplied through Red Hat packages.

Validation and detection

  • Inventory Unbound installations and record exact software or distribution package versions.
  • Confirm each installation is version 1.25.1 or includes the vendor’s backported fix.
  • Verify which resolvers accept queries from internet or untrusted network segments.
  • Monitor DNS latency, thread utilization, and service availability for unexplained saturation.
  • Confirm change records identify the CVE-specific patch or package advisory.
Prepared
Confidence
high
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-1050: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-407: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-770: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-41292 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
12Timeline events
2ADP providers
9Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat-SADP
6.6CVSS 4.0MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Red——NLnet Labs

Vulnerability scoring details

Base CVSS 4.0 score

6.6Medium
CVSS 4.0 vector shape for CVE-2026-41292Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Red

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. Source timelineNLnet Labs

    Issue reported by N0zoM1z0

  2. Source timelineNLnet Labs

    NLnet Labs shares patch

  3. Source timelineNLnet Labs

    N0zoM1z0 verifies patch

  4. Source timelineNLnet Labs

    Issue also reported by Qifan Zhang

  5. Source timelineNLnet Labs

    NLnet Labs shares same patch

  6. Source timelineNLnet Labs

    Qifan Zhang verifies patch

  7. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  8. Source timelineNLnet Labs

    Fixes released with version 1.25.1

  9. ADP timelineredhat-SADP

    Made public.

  10. CVE publishedCVE Program

    The CVE record was published.

  11. ADP timelineredhat-SADP

    Reported to Red Hat.

  12. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPunbound: Unbound: Denial of Service via excessive EDNS options
other:Red Hat severity ratingcvssV3_1
  • 2026-05-20T10:00:54.433Z: Reported to Red Hat.
  • 2026-05-20T09:19:13.022Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
NLnet LabsUnbound0unaffected
Weakness

CWE details

CWE-1050CWE-407CWE-770

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.