CVE Intelligence
High Memory corruption

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.

Published Mar 24, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: f5

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 25.1% (30-day exploitation probability)+15
  • Technical severity (high)+6
  • Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
25.07%
ahead of 98% of scored CVEs · Oct 14, 2026
Affects
F5
Nginx Open Source and 1 more
CVSS base
8.2
High · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
Yes
can an attacker script the kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (F5 Nginx Open Source, F5 Nginx Plus).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  4. EPSS ahead of 98% of scored CVEs: prioritize it in the patch queue.
  5. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
F5 Nginx Open Source ≥ 0.5.13 and < 1.28.3≥ 1.29.0 and < 1.29.7 Vulnerable CVE Program (cve.org) e CISA ADP
F5 Nginx Open Source ≥ 1.29.0 and < 1.29.7≥ 1.0.0 and < 1.28.3≥ 0.5.13 and ≤ 0.9.7 Vulnerable NIST National Vulnerability Database
F5 Nginx Plus version r36version r36-p2version r36-p1version r32-p1version r35-p1version r35version r34-p2version r34-p1
and 8 more version r34version r33-p3version r33-p2version r33-p1version r33version r32-p4version r32-p3version r32-p2
Vulnerable NIST National Vulnerability Database
F5 Nginx Plus ≥ R32 and < R32 P5≥ R33≥ R34≥ R35 and < R35 P2≥ R36 and < R36 P3 Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
8.8 CVSS 4.0 High — — f5sirt@f5.com via NIST National Vulnerability Database
8.8 CVSS 4.0 High — — f5 via CVE Program (cve.org) e CISA ADP
8.2 CVSS 3.1 High 3.9 4.2 f5sirt@f5.com via NIST National Vulnerability Database
8.2 CVSS 3.1 High 3.9 4.2 0b0ca135-0b70-47e7-9f44-1890c2a1c46c via NIST National Vulnerability Database
8.2 CVSS 3.1 High — — f5 via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H (score shown at the top: f5sirt@f5.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-122 · Heap-based Buffer Overflow

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 25.07%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
web/proxy/WAF logsnetwork IDS/IPSendpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · f5/nginx open source, f5/nginx plus
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 13, 2026
  • CVSS changed · 8.2
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · → Modified
    Oct 13, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVE published
    Mar 24, 2026 · f5

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

19 on the record

Elsewhere on this site

F5
every CVE for this vendor
Memory corruption
same class
CWE-122
other pages naming this weakness

Related CVEs (same products)

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-27654 is "NGINX ngx_http_dav_module vulnerability", rated High. It affects Nginx Open Source (F5); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.2 describes technical severity. EPSS 25.07% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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