Security readout for executives and security teams
Plain-English summary
A critical NGINX memory-safety flaw can let an unauthenticated attacker crash worker processes with crafted HTTP requests when a specific configuration is present. Code execution may be possible if ASLR is disabled or bypassed. The issue affects data-plane traffic handling, not the control plane. The provided sources do not establish active exploitation.
Executive priority
Treat this as an urgent validation and remediation item for internet-facing NGINX systems. Configuration prerequisites reduce broad exposure, but reachable vulnerable instances face service disruption and potentially code execution. Require owners to confirm configuration exposure and follow F5’s patch guidance promptly.
Technical view
A heap buffer overflow can occur when an NGINX map uses regex matching and an expression references regex capture variables before the map output variable. Certain uses of non-cacheable variables may also trigger it. Successful exploitation can restart a worker, causing denial of service, and may enable code execution where ASLR is absent or bypassed.
Likely exposure
Exposure is configuration-dependent. Prioritize NGINX Plus and NGINX Open Source systems receiving untrusted HTTP traffic that use regex-based map directives or relevant non-cacheable variables. The bundle lists Plus 37.0.0.1, R36, and R33, and Open Source 1.31.2 and 0.9.6, but marks default affected status unknown.
Exploitation context
An unauthenticated remote attacker can send crafted HTTP requests, but exploitation requires configuration and runtime conditions partly beyond the attacker’s control. The CVSS 4.0 score is 9.2 with high attack complexity. The bundle reports KEV as false and provides no other evidence of active exploitation.
Researcher notes
The weakness is classified as CWE-122 and scored 9.2 under CVSS 4.0. Scope assessment is limited because the bundle does not include explicit fixed versions, exact affected ranges, or the alternate non-cacheable-variable conditions. End-of-Technical-Support releases were not evaluated, so absence from the listed versions does not establish safety.
Mitigation direction
- Review F5 advisory K000162097 and apply vendor-specified patched releases for each supported NGINX deployment.
- Prioritize internet-facing data-plane instances using affected map and regex configurations.
- If patching is delayed, seek vendor-approved workarounds; none are specified in the provided bundle.
- Preserve ASLR protections; disabling ASLR increases potential impact according to the source.
Validation and detection
- Inventory NGINX Plus and Open Source versions, including unsupported deployments not evaluated by F5.
- Inspect configurations for map directives referencing regex capture variables before the map output variable.
- Identify string expressions containing non-cacheable variables that may meet the alternate vulnerable condition.
- Confirm deployed versions and remediation status against F5 advisory K000162097.
- Monitor worker crashes or restarts associated with crafted or unusual HTTP requests.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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-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.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-42533 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.2 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
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.
SSVC decision data
CVSS vector scores
2 official scoresWe 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.
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N——f5CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H2.25.9f5Vulnerability scoring details
Base CVSS 4.0 score
9.2CriticalVector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Base CVSS 3.1 score
8.1HighVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://my.f5.com/manage/s/article/K000162097CVE reference, f5 · vendor-advisory, patch
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
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.