What is CVE-2026-42946?
A vulnerability exists in the ngx_http_scgi_module and ngx_http_uwsgi_module modules that may result in excessive memory allocation or an over-read of data. When scgi_pass or uwsgi_pass is configured, an unauthenticated attacker with man-in-the-middle (MITM) ability to control responses from an upstream server may be able to read the memory of the NGINX worker process or restart it. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
The record classifies CVE-2026-42946 under weakness classes CWE-789, CWE-823. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality. 2 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 167 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 6.5 — MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:L - CVSS v4.0 base score
- 8.3
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:L/SC:N/SI:N/SA:N - EPSS (FIRST)
- 0.9% probability of exploitation in the next 30 days, higher than 59.5% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 5.6/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-05-13
Is CVE-2026-42946 being exploited?
It currently carries a trending score of 20 in the Threadlinqs vulnerability feed.
Affected products and versions
- F5: NGINX Plus, NGINX Open Source
How to fix CVE-2026-42946
Vendor advisory: https://my.f5.com/manage/s/article/K000161027. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.
Threat activity tracking CVE-2026-42946
1 tracked threat in the Threadlinqs corpus references CVE-2026-42946, either in the campaign’s CVE list or as an indicator on the campaign record.
Sources
Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on . This product uses the NVD API but is not endorsed or certified by the NVD.