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CVE Record

CVE-2026-27654: NGINX ngx_http_dav_module vulnerability

NGINX Open Source and NGINX Plus have a vulnerability in the ngx_http_dav_module module that might allow an attacker to trigger a buffer overflow to the NGINX worker process; this vulnerability may result in termination of the NGINX worker process or modification of source or destination file names outside the document root. This issue affects NGINX Open Source and NGINX Plus when the configuration file uses DAV module MOVE or COPY methods, prefix location (nonregular expression location configuration), and alias directives. The integrity impact is constrained because the NGINX worker process user has low privileges and does not have access to the entire system. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

HighCVSS 8.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This flaw affects certain NGINX WebDAV configurations. A remote attacker may be able to crash an NGINX worker process or alter source or destination filenames outside the document root. The issue is high priority where public NGINX instances use DAV MOVE or COPY with alias-based prefix locations.

Executive priority

Prioritize internet-facing NGINX systems that support WebDAV. Business risk is mainly service disruption and constrained file-name integrity impact, not full system compromise based on the provided sources.

Technical view

CVE-2026-27654 is a buffer overflow in ngx_http_dav_module. It requires a specific configuration: DAV MOVE or COPY methods, a non-regex prefix location, and alias directives. The CVSS 4.0 score is 8.8, with network attack vector, low complexity, no privileges, and high availability impact.

Likely exposure

Exposure is likely limited to NGINX Open Source or NGINX Plus deployments that enable ngx_http_dav_module and the vulnerable DAV, location, and alias configuration combination.

Exploitation context

The bundle does not identify active exploitation, and KEV is false. The CVSS vector indicates remote, unauthenticated, low-complexity attack conditions if the vulnerable configuration is present.

Researcher notes

The vulnerable condition is configuration-dependent. Integrity impact is described as constrained because the NGINX worker user has low privileges. The source bundle does not provide proof-of-concept details, precise fixed upstream versions, or evidence of exploitation.

Mitigation direction

  • Review F5 guidance for affected NGINX Open Source and NGINX Plus versions.
  • Apply F5 or distribution security updates where applicable.
  • Check Red Hat RHSA advisories if using Red Hat-packaged NGINX.
  • Disable or redesign the vulnerable DAV MOVE/COPY plus alias configuration where feasible.
  • Restrict WebDAV exposure while vendor remediation is pending.

Validation and detection

  • Inventory NGINX Open Source and NGINX Plus deployments.
  • Check whether ngx_http_dav_module is enabled or built into deployed instances.
  • Inspect configs for DAV MOVE or COPY methods with prefix locations and alias directives.
  • Confirm whether deployed versions match F5 or distribution affected-version guidance.
  • Verify updated packages against F5 or Red Hat advisory status.
Prepared
Confidence
high
Sources
12

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-120: 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.

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cwe · low confidence lookup

CWE-122: 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.

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cve · low confidence lookup

CVE-2026-27654 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.8 (4.0)
Known Exploited
No
Published

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

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.

3CVSS vectors
5Timeline events
2ADP providers
20Source links

SSVC decision data

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

CVSS vector scores

3 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
8.8CVSS 4.0HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N——f5
8.2CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H3.94.2f5
8.2CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H3.94.2redhat-SADP

Vulnerability scoring details

Base CVSS 4.0 score

8.8High
CVSS 4.0 vector shape for CVE-2026-27654Attack 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:L/VA:H/SC:N/SI:N/SA:N

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. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

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

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPNGINX: NGINX: Denial of Service or file modification via buffer overflow in ngx_http_dav_module
other:Red Hat severity ratingcvssV3_1
  • 2026-03-24T15:01:19.814Z: Reported to Red Hat.
  • 2026-03-24T14:13:26.879Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
F5NGINX Open Source1.29.0, 0.5.13unknown
F5NGINX PlusR36, R35, R34, R33, R32unknown
Weakness

CWE details

CWE-120CWE-122

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

CWE-120 · source CWE mapping

Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-122 · source CWE mapping

Heap-based Buffer Overflow

Heap-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs