CVE-2026-42926: f5 nginx gateway fabric Encoding Error
CVSS: 6.3v4.0MediumAnalyzed
AliasesALPINE-CVE-2026-42926UBUNTU-CVE-2026-42926DEBIAN-CVE-2026-42926CGA-9p6v-625p-42chCGA-f346-6497-gmw3CGA-mv86-rqmq-mg6pCGA-p9qx-9r4h-xxg7
Published 13-05-2026Last modified 13-05-2026
Vulnerability summary
CVE-2026-42926 is a medium (CVSS 6.3) Encoding Error vulnerability in f5 nginx gateway fabric. EPSS estimates a 0.34% chance of exploitation in the next 30 days, higher than 25.6% of scored vulnerabilities.
CVSS score
6.3/10
010
Medium · v4.0 (CVE.org)EPSS score
0.34%
0%100%
Low · -0.01 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 3 · Related 2Timeline
- 13-05-2026PublishedVulnerability first disclosed.
- 13-05-2026Last modifiedVulnerability information updated.
Description
When NGINX Open Source is configured to proxy HTTP/2 traffic by setting proxy_http_version to 2, and also uses proxy_set_body, an attacker may be able to inject frame headers and payload bytes to the upstream peer. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
CVSS metrics
10 scores · 7 sources · 2 versionsMedium 6.3Preferred score · CVE.org (CNA)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:NSourcesAll 7 agree
- OSV · AlpineEcosystem advisory · calculated6.3MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/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
- OSV · UbuntuEcosystem advisory · calculated6.3MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N
- OSV · DebianEcosystem advisory · calculated6.3MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/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
- OSV · WolfiEcosystem advisory · calculated6.3MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/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
- OSV · ChainguardEcosystem advisory · calculated6.3MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/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
- NVDNIST6.3MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/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
Medium 5.8Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:NSourcesAll 3 agree
- OSV · UbuntuEcosystem advisory · calculated5.8MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
- NVDNIST5.8MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
EPSS trend
Probability
0.34%
Chance of exploitation in the next 30 days
Percentile
26%
Versus all other CVEs
30-day change
-0.01 pp
From 0.35% on 18-09-2026
18-09-202618-10-2026
EPSS score0.34%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
F54 products
- nginx gateway fabric≥ 1.3.0, ≤ 1.6.2 | ≥ 2.0.0, ≤ 2.6.0
- nginx ingress controller≥ 3.5.0, ≤ 3.7.2 | ≥ 4.0.0, ≤ 4.0.1 | ≥ 5.0.0, ≤ 5.4.2
- nginx_instance_manager≥ 2.16.0, ≤ 2.22.0
- nginx open source≥ 1.29.4, < 1.30.1 | ≥ 1.29.4, ≤ 1.30.0
Chainguard2 products
- nginx-mainline< 1.31.0-r0
- nginx-stable< 1.30.1-r0
Wolfi2 products
- nginx-mainline< 1.31.0-r0
- nginx-stable< 1.30.1-r0
Alpine1 product
- nginxAll versions (No fix recorded)
Debian1 product
- nginx< 1.30.0-4
Ubuntu1 product
- nginxAll versions (No fix recorded)
6 vendors · 11 products
