How severe is CVE-2026-42926?

CVE-2026-42926 has a CVSS 3.x base score of 5.8, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2026-42926 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (26th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-42926?

CVE-2026-42926 primarily affects F5 Nginx Gateway Fabric. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-42926?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-42926 have an EU (EUVD) identifier?

Yes. CVE-2026-42926 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30006.

When was CVE-2026-42926 published?

CVE-2026-42926 was published on 2026-05-13 and last updated on 2026-06-18.

CVE-2026-42926

CVE-2026-42926 is a medium-severity vulnerability in F5 Nginx Gateway Fabric with a CVSS 3.x base score of 5.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-172.

Key facts

Severity: Medium (CVSS 3.x base score 5.8)
CVSS v4: 6.3
EPSS exploit prediction: 0% (26th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-30006
Weakness: CWE-172
Affected product: F5 Nginx Gateway Fabric
Published: 2026-05-13
Last modified: 2026-06-18

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.

Frequently asked questions

What is CVE-2026-42926?: 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.
How severe is CVE-2026-42926?: CVE-2026-42926 has a CVSS 3.x base score of 5.8, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2026-42926 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (26th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-42926?: CVE-2026-42926 primarily affects F5 Nginx Gateway Fabric. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-42926?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-42926 have an EU (EUVD) identifier?: Yes. CVE-2026-42926 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30006.
When was CVE-2026-42926 published?: CVE-2026-42926 was published on 2026-05-13 and last updated on 2026-06-18.

References

https://my.f5.com/manage/s/article/K000161131

Affected products (4)

cpe:2.3:a:f5:nginx_gateway_fabric:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_open_source:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_instance_manager:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:*:*:*:*

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