Ngx_http_v3_module: memory corruption

nginx

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.

Fix it

NGINX Open Source

On 1.xUpgrade to NGINX Open Source 1.31.2
On 2.xUpgrade to NGINX Open Source 2.6.4
On 5.xUpgrade to NGINX Open Source 5.5.1

First seen: 28 Oct 2026
Last update: 28 Oct 2026, 04:17 UTC
Fixed in: 5.5.1
2.6.4
1.31.2
Identifiers: CVE-2026-42530
CVSS: 8.1
Source: news
On the menu as: nginx

Check this repository for exposure to one security incident from pwned.coffee. Report first, change nothing until I say so.

## Ngx_http_v3_module: memory corruption
Severity: high. Patch status: patched.
Affected: nginx
Fixed in: 5.5.1, 2.6.4, 1.31.2
Ids: CVE-2026-42530

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.

## Steps
1. This touches infrastructure (nginx). Look in terraform, ansible, cloud-init, Dockerfiles and docs for the product and version we run. If it isn't in the repo, say so and list what a human should check on the box.
2. Fix by release line: NGINX Open Source: 5.5.1; 2.6.4; 1.31.x → 1.31.2.

## Fix by release line
| Line | State | Fix | Until then |
|---|---|---|---|
| NGINX Open Source | fixed | 5.5.1 | — |
| NGINX Open Source | fixed | 2.6.4 | — |
| NGINX Open Source 1.31.x | fixed | 1.31.2 | — |

## Report
A table: file, product or package, version in use, affected yes/no, exact fix. Then anything a human has to check outside the repo.

If you have the pwned.coffee MCP server (https://pwned.coffee/mcp), call lookup_cve("CVE-2026-42530") for the latest, and check_repo with this repo's lockfiles, Dockerfiles and workflows for a full receipt.
Sources: https://my.f5.com/manage/s/article/K000161616 https://nvd.nist.gov/vuln/detail/CVE-2026-42530
https://pwned.coffee/i/ngx-http-v3-module-memory-corruption-cve-2026-42530

Timeline

28 Oct 2026, 04:18 UTC
Fix status: unknown → patched.
28 Oct 2026
First reported.

Receipt

Exploitation: No known exploitation
Fix by release line: Product Affected Fixed in Source
NGINX Open Source before 5.5.1 5.5.1 NVD checked 28 Oct
NGINX Open Source before 2.6.4 2.6.4 NVD checked 28 Oct
NGINX Open Source 1.31.0 to before 1.31.2 1.31.2 CVE record (CNA) checked 28 Oct
Score: CVSS 8.1 (high). CVSS 3.1 8.1 (CNA f5) for CVE-2026-42530
Last checked: 28 Oct 2026, 04:18 UTC

Product	Affected	Fixed in	Source
NGINX Open Source	before 5.5.1	5.5.1	NVD checked 28 Oct
NGINX Open Source	before 2.6.4	2.6.4	NVD checked 28 Oct
NGINX Open Source	1.31.0 to before 1.31.2	1.31.2	CVE record (CNA) checked 28 Oct

Sources: KEV – CVE record ✓ Vendor ✓

Sources

Wrong fix version, or a source we missed? Send it back to chef@pwned.coffee with the source, and we'll correct it here.

Totalone hot coffee