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High, CVSS 8.2

amphp/http-client Denial of Service via HTTP/2 CONTINUATION Frames

GHSA-w8gf-g2vq-j2f4

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (amphp/http-client 4.1.0-rc1), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
8.2 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
EPSS
No dated EPSS signal available.
Source description

As published by the source; long descriptions are shortened.

Early versions of amphp/http-client with HTTP/2 support (v4.0.0-rc10 to 4.0.0) will collect HTTP/2 CONTINUATION frames in an unbounded buffer and will not check the header size limit until it has received the ENDHEADERS flag, resulting in an OOM crash. Later versions of amphp/http-client (v4.1.0-rc1 and up) depend on amphp/http for HTTP/2 processing and will therefore need an updated version of amphp/http, see GHSA-qjfw-cvjf-f4fm. Acknowledgements Thank you to Bartek Nowotarski for reporting the vulnerability.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-w8gf-g2vq-j2f4

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: GHSA-w8gf-g2vq-j2f4

Advisory: amphp/http-client Denial of Service via HTTP/2 CONTINUATION Frames
IDs: GHSA-w8gf-g2vq-j2f4
Record: https://patchnext.com/advisories/ghsa-w8gf-g2vq-j2f4 (revision 1, source checked 26 Oct 2026, 14:19 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: amphp/http-client 4.1.0-rc1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist amphp/http-client: affected >= 4.0.0-rc10, <= 4.0.0; fixed in 4.1.0-rc1

## Suggested inspection (read-only)
- Packagist amphp/http-client: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on amphp/http-client.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-w8gf-g2vq-j2f4 (GitHub-reviewed advisory GHSA-w8gf-g2vq-j2f4 lists affected ranges: Packagist amphp/http-client >=4.0.0-rc10 <=4.0.0)

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