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CVE-2026-42530

NGINX Open-Source ngx_http_v3_module vulnerability

9.2 CriticalPublic exploitFix available

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 Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

6.22%Up 5.5 points since Jun 18, 2026
90%50%10%1%

What each source reports

CVE List Score used 9.2

NGINX Open-Source ngx_http_v3_module vulnerability

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 Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Record
CVE-2026-42530
CVSS 4.0
9.2 CriticalCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-416, CWE-416
Updated
2026-11-02
EUVDEUVD-2026-37717 9.2

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 Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Record
EUVD-2026-37717
CVSS 4.0
9.2 CriticalCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-5mcp-3252-f5vr 9.2

NGINX Open Source has a vulnerability in the ngx_http_v3_module module. When NGINX Open Source is...

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 Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Record
GHSA-5mcp-3252-f5vr
CVSS 4.0
9.2 CriticalCVSS: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 3.1
8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-416
Updated
2026-11-02
NVD 9.2

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 Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Record
CVE-2026-42530
CVSS 4.0
9.2 CriticalCVSS: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 3.1
8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-416
Updated
2026-11-02
OSV 9.2

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 Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Record
CVE-2026-42530
CVSS 4.0
9.2 CriticalCVSS: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
Updated
2026-11-02
OSVDEBIAN-CVE-2026-42530 9.2

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 Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Record
DEBIAN-CVE-2026-42530
CVSS 4.0
9.2 CriticalCVSS: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
Updated
2026-11-02
Show 5 moreShow less
OSVRHSA-2026:20351 8.1

Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update

Record
RHSA-2026:20351
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVBIT-nginx-2026-42530 No score

NGINX Open-Source ngx_http_v3_module vulnerability

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 Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Record
BIT-nginx-2026-42530
Updated
2026-11-02
OSVBIT-nginx-gateway-2026-42530 No score

NGINX Open-Source ngx_http_v3_module vulnerability

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 Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Record
BIT-nginx-gateway-2026-42530
Updated
2026-11-02
OSVopenSUSE-SU-2026:11066-1 No score

nginx-1.31.2-1.1 on GA media

These are all security issues fixed in the nginx-1.31.2-1.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2026:11066-1
Updated
2026-11-02
OSVUBUNTU-CVE-2026-42530 No score

(NGINX Open Source has a vulnerability in the ngx_http_v3_modulemodule. ...)

Record
UBUNTU-CVE-2026-42530
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
nginx
Bitnami
 1.31.0 up to 1.31.2
1.31.2
nginx-gateway
Bitnami
 1.31.0 up to 1.31.2
1.31.2
nginx
Red Hat:hummingbird:1
From an advisory covering 4 CVEs
 before 0:1.30.2-1.hum1
0:1.30.2-1.hum1
nginx-all-modules
Red Hat:hummingbird:1
From an advisory covering 4 CVEs
 before 0:1.30.2-1.hum1
0:1.30.2-1.hum1
nginx-core
Red Hat:hummingbird:1
From an advisory covering 4 CVEs
 before 0:1.30.2-1.hum1
0:1.30.2-1.hum1
nginx-filesystem
Red Hat:hummingbird:1
From an advisory covering 4 CVEs
 before 0:1.30.2-1.hum1
0:1.30.2-1.hum1
nginx-mod-devel
Red Hat:hummingbird:1
From an advisory covering 4 CVEs
 before 0:1.30.2-1.hum1
0:1.30.2-1.hum1
nginx-mod-http-geoip
Red Hat:hummingbird:1
From an advisory covering 4 CVEs
 before 0:1.30.2-1.hum1
0:1.30.2-1.hum1
nginx-mod-http-image-filter
Red Hat:hummingbird:1
From an advisory covering 4 CVEs
 before 0:1.30.2-1.hum1
0:1.30.2-1.hum1
nginx-mod-http-perl
Red Hat:hummingbird:1
From an advisory covering 4 CVEs
 before 0:1.30.2-1.hum1
0:1.30.2-1.hum1
Show 5 moreShow less
Affected packages
PackageAffectedFixed
nginx-mod-http-xslt-filter
Red Hat:hummingbird:1
From an advisory covering 4 CVEs
 before 0:1.30.2-1.hum1
0:1.30.2-1.hum1
nginx-mod-mail
Red Hat:hummingbird:1
From an advisory covering 4 CVEs
 before 0:1.30.2-1.hum1
0:1.30.2-1.hum1
nginx-mod-stream
Red Hat:hummingbird:1
From an advisory covering 4 CVEs
 before 0:1.30.2-1.hum1
0:1.30.2-1.hum1
nginx-mod-stream-geoip
Red Hat:hummingbird:1
From an advisory covering 4 CVEs
 before 0:1.30.2-1.hum1
0:1.30.2-1.hum1
nginx
openSUSE:Tumbleweed
From an advisory covering 3 CVEs
 before 1.31.2-1.1
1.31.2-1.1

Public exploits

Links only. Every CVE stores no exploit code.

Public exploits
SourceLinkDate
PoC in GitHub0xBlackash/CVE-2026-425302026-06-19
PoC in GitHubHORKimhab/CVE-2026-425302026-06-19
PoC in GitHubv4ltonn/CVE-2026-425302026-06-19

History

History
RecordedChangedSources
affected, facts
affected
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV, PoC in GitHub

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-42530 is a critical vulnerability (CVSS 9.2) in F5 Nginx Open Source, published May 26, 2026. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 6.22%, the 93rd percentile. Fixed in nginx 1.31.2.

References

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