CVE-2026-42530: NGINX Open Source has a vulnerability in the ngx_http_v3_module module

This week

HIGH 8.1REMOTEWATCHLISTUPGRADEUPGRADEUPGRADE

CVE-2026-42530 is a high-severity flaw (CVSS 8.1) affecting nginx gateway fabric, nginx ingress controller, nginx instance manager. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

NGINX Open Source has a vulnerability in the ngx_http_v3_module module. When NGINX Open Source is configured to use the HTTP/3 QUIC module, a remote unauthenticated attacker along with conditions beyond their control can use a specially crafted HTTP/3 session to reopen a QPACK encoder stream. This may cause a Use-after-Free in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Lay

Why this priority

High severity
EPSS top 6%: very likely to be exploited
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	6.5% (top 6%)
CISA exploited list	No
Weakness	CWE-416
Published	2026-06-17
Last modified	2026-10-26

Publisher (CNA): F5 Networks · Vendor: f5

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-17 15:16 UTCPublished CVE record published
2026-10-26 12:10 UTCUpdated Record last modified

f5 nginx gateway fabric UPGRADE

Affected: >= 1.3.0 and <= 1.6.2 · >= 2.0.0 and < 2.6.4

Fixed in: 2.6.4

Safe to downgrade to: a release before 1.3.0

1. Check installed version

apt-cache policy nginx-gateway-fabric || rpm -q nginx-gateway-fabric || nginx-gateway-fabric --version

2. UPGRADE to 2.6.4 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade nginx-gateway-fabric

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade nginx-gateway-fabric

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 1.3.0 (Debian / Ubuntu)

apt-cache madison nginx-gateway-fabric sudo apt install nginx-gateway-fabric=<VERSION_BEFORE_1.3.0> sudo apt-mark hold nginx-gateway-fabric

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list nginx-gateway-fabric sudo dnf downgrade nginx-gateway-fabric-<VERSION_BEFORE_1.3.0> sudo dnf versionlock add nginx-gateway-fabric

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

f5 nginx ingress controller UPGRADE

Affected: >= 3.5.0 and <= 3.7.2 · >= 5.0.0 and < 5.5.1 · 4.0.0 · 4.0.1

Fixed in: 5.5.1

Safe to downgrade to: a release before 3.5.0

1. Check installed version

apt-cache policy nginx-ingress-controller || rpm -q nginx-ingress-controller || nginx-ingress-controller --version

2. UPGRADE to 5.5.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade nginx-ingress-controller

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade nginx-ingress-controller

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 3.5.0 (Debian / Ubuntu)

apt-cache madison nginx-ingress-controller sudo apt install nginx-ingress-controller=<VERSION_BEFORE_3.5.0> sudo apt-mark hold nginx-ingress-controller

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list nginx-ingress-controller sudo dnf downgrade nginx-ingress-controller-<VERSION_BEFORE_3.5.0> sudo dnf versionlock add nginx-ingress-controller

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

f5 nginx instance manager UPGRADE

Affected: >= 2.17.0 and <= 2.22.0

Fixed in: newer than 2.22.0

Safe to downgrade to: a release before 2.17.0

1. Check installed version

apt-cache policy nginx-instance-manager || rpm -q nginx-instance-manager || nginx-instance-manager --version

2. UPGRADE to newer than 2.22.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade nginx-instance-manager

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade nginx-instance-manager

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.17.0 (Debian / Ubuntu)

apt-cache madison nginx-instance-manager sudo apt install nginx-instance-manager=<VERSION_BEFORE_2.17.0> sudo apt-mark hold nginx-instance-manager

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list nginx-instance-manager sudo dnf downgrade nginx-instance-manager-<VERSION_BEFORE_2.17.0> sudo dnf versionlock add nginx-instance-manager

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

f5 nginx open source UPGRADE

Affected: >= 1.31.0 and < 1.31.2

Fixed in: 1.31.2

Safe to downgrade to: a release before 1.31.0

1. Check installed version

apt-cache policy nginx-open-source || rpm -q nginx-open-source || nginx-open-source --version

2. UPGRADE to 1.31.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade nginx-open-source

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade nginx-open-source

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 1.31.0 (Debian / Ubuntu)

apt-cache madison nginx-open-source sudo apt install nginx-open-source=<VERSION_BEFORE_1.31.0> sudo apt-mark hold nginx-open-source

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list nginx-open-source sudo dnf downgrade nginx-open-source-<VERSION_BEFORE_1.31.0> sudo dnf versionlock add nginx-open-source

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

Fedora 46 · flare-im · FIXED · 0.22.7-1.fc46 · FEDORA-2026-cd5e8062a1 · source

sudo dnf upgrade --advisory=FEDORA-2026-cd5e8062a1

Fedora ELN · libdnf · FIXED · 0.76.0-2.eln159 · FEDORA-2026-dbd263e9d4 · source

sudo dnf upgrade --advisory=FEDORA-2026-dbd263e9d4

Debian 12 · nginx · NOT AFFECTED

Debian 13 · nginx · NOT AFFECTED

RHEL 10 · nginx · NOT AFFECTED

RHEL 8 · nginx · NOT AFFECTED

RHEL 8 · nginx:1.24/nginx · NOT AFFECTED

RHEL 9 · nginx · NOT AFFECTED

RHEL 9 · nginx:1.24/nginx · NOT AFFECTED

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: v4ltonn/CVE-2026-42530 (5 stars)
GitHub PoC: 0xBlackash/CVE-2026-42530 (3 stars)
GitHub PoC: HORKimhab/CVE-2026-42530 (0 stars)

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-42530?

nginx gateway fabric: upgrade to 2.6.4; nginx ingress controller: upgrade to 5.5.1; nginx instance manager: upgrade to newer than 2.22.0. Exact commands for each OS are on this page.

Is CVE-2026-42530 being exploited?

CVE-2026-42530 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-42530 affect?

CVE-2026-42530 affects nginx gateway fabric, nginx ingress controller, nginx instance manager. Severity is high (CVSS 8.1). NGINX Open Source has a vulnerability in the ngx_http_v3_module module. When NGINX Open Source is configured to use the HTTP/3 QUIC module, a remote unauthenticated attacker along with conditions beyond their control can use a specially cra

How urgent is CVE-2026-42530?

Priority 62/100. High severity; EPSS top 6%: very likely to be exploited; Remotely exploitable, no login, no user action; On your watchlist

Software pages

nginx vulnerabilities · F5 BIG-IP vulnerabilities

Related CVEs

CVE-2026-40460 MEDIUM 6.5 UPGRADE UPGRADE When NGINX Plus or NGINX Open Source are configured to use the HTTP/3 QUIC module, an attacker may be able to
CVE-2026-40701 MEDIUM 4.8 UPGRADE UPGRADE NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssl_module module when the ssl_verify_cl
CVE-2026-42945 HIGH 8.1 UPGRADE UPGRADE NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module
CVE-2026-42946 MEDIUM 6.5 UPGRADE UPGRADE A vulnerability exists in the ngx_http_scgi_module and ngx_http_uwsgi_module modules that may result in excess
CVE-2026-42934 MEDIUM 4.8 UPGRADE UPGRADE NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_charset_module module

References

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