dbcve.org
Double FreeWeakness · CWE-415

CVE-2026-12043

HIGH · 8.8 CVSS v3.1 Published 2026-06-12
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The vulnerability exists in the HPACK (HTTP/2 header compression) implementation within the aws-c-http library. A malicious HTTP/2 server can send crafted HEADERS frames containing improper dynamic table size updates, causing memory corruption on the client. This memory corruption can potentially be exploited for arbitrary code execution.

MitigationUpgrade aws-c-http library to version 0.11.0 or later to obtain the patch for proper HPACK dynamic table size update validation.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Locate aws-c-http library version
    Search for the aws-c-http library in your project's dependencies (conanfile.txt, vcpkg.json, package.json, CMakeLists.txt, or similar) or check the installed library version via your package manager (conan search aws-c-http, vcpkg list, or find the version in /usr/lib/pkgconfig/aws-c-http.pc on Linux)
    Affected if The installed version is lower than 0.11.0 or the version cannot be determined (unpatched)
  2. Confirm HTTP/2 client functionality is in use
    Search your codebase for aws-c-http API calls that establish HTTP/2 connections, such as aws_http_connection_manager_create with HTTP/2 protocol negotiation, or aws_http_client_connect with alpn_protocols set to "h2"
    Affected if Your application acts as an HTTP/2 client using aws-c-http to connect to servers
  3. Verify HPACK decompression is active
    Inspect your application's runtime configuration or debug logs for HTTP/2 header compression activity. HPACK is the compression scheme used exclusively for HTTP/2 headers. If your app processes HTTP/2 responses with compressed headers, HPACK is active
    Affected if The library processes incoming HEADERS frames from HTTP/2 servers (this is the default behavior for HTTP/2 responses)
  4. Compare version against fixed release
    If you identified a version number in step 1, compare it to the fixed version 0.11.0. Versions prior to 0.11.0 do not contain the HPACK dynamic table size update validation fix
    Affected if The identified version is below 0.11.0 (for example: 0.10.0, 0.9.0, or any pre-0.11.0 release)

You are affected if your application uses aws-c-http library version below 0.11.0 as an HTTP/2 client that decompresses headers from servers, because the vulnerability triggers when a malicious server sends specially crafted HEADERS frames with improper dynamic table size updates.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade aws-c-http library to version 0.11.0 or later to obtain the patch for proper HPACK dynamic table size update validation.

Recommended fix High confidence

aws-c-http version 0.11.0

  1. Identify the current aws-c-http library version in your project by checking your dependency manifest (e.g., package.json, requirements.txt, CMakeLists.txt, or your lock file)
  2. Update your dependency specification to aws-c-http version 0.11.0
  3. Run your package manager's update command to fetch the new version (e.g., pip install -U, cargo update, or cmake rebuild)
  4. Rebuild your application to link against the updated library
  5. Test your application to verify HTTP/2 functionality works correctly after the upgrade

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,190
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-12043 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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