NGINX map directive and regex matching vulnerability
Summary
| CVE | CVE-2026-93479 |
|---|---|
| State | PUBLISHED |
| Assigner | f5 |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-10-14 15:17:26 UTC |
| Updated | 2026-10-14 16:04:11 UTC |
| Description | A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and the root directive or access log format references the map's regex capture variables before referencing the map output variable. Alternatively, the same result could be achieved by using a non-cacheable variable in a string expression under certain conditions. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated. |
Risk And Classification
Primary CVSS: v4.0 9.2 CRITICAL from [email protected]
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Problem Types: CWE-122 | CWE-122 CWE-122 Heap-based Buffer Overflow
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 9.2 | CRITICAL | 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/E:X/C... |
| 4.0 | CNA | CVSS | 9.2 | CRITICAL | 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 |
| 3.1 | [email protected] | Primary | 8.1 | HIGH | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | CNA | CVSS | 8.1 | HIGH | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
CVSS v4.0 Breakdown
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | F5 | NGINX Plus | affected 37.1.0 37.1.0.1 custom | Not specified |
| CNA | F5 | NGINX Plus | affected 37.0.0 37.0.5.1 custom | Not specified |
| CNA | F5 | NGINX Plus | affected R36 * custom | Not specified |
| CNA | F5 | NGINX Plus | affected R35 * custom | Not specified |
| CNA | F5 | NGINX Plus | affected R34 * custom | Not specified |
| CNA | F5 | NGINX Plus | affected R33 * custom | Not specified |
| CNA | F5 | NGINX Open Source | affected 1.31.2 1.31.7 custom | Not specified |
| CNA | F5 | NGINX Open Source | affected 1.30.0 1.30.6 custom | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| my.f5.com/manage/s/article/K000162607 | [email protected] | my.f5.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: F5 acknowledges "Matt Suiche" of "Tolmo, Inc." and "Mateusz Gierblinski " for bringing this issue to our attention and following the highest standards of coordinated disclosure. (en)
Additional Advisory Data
Workarounds
CNA: To mitigate this vulnerability, do not use unnamed captures. Use named captures instead and limit their usage to the block with the regex match.