HTTP/2 HPACK integer overflow and buffer allocation

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2023-36478: 4.83% estimated exploitation activity in the next 30 days; percentile 92.00 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

An integer overflow in MetaDataBuilder.checkSize allows for HTTP/2 HPACK header values to exceed their size limit. In MetaDataBuilder.java, the following code determines if a header name or value exceeds the size limit, and throws an exception if the limit is exceeded: However, when length is very large and huffman is true, the multiplication by 4 in line 295 will overflow, and length will become negative. (size+length) will now be negative, and the check on line 296 will not be triggered. Furthermore, MetaDataBuilder.checkSize allows for user-entered HPACK header value sizes to be negative, potentially leading to a very large buffer allocation later on when the user-entered size is multiplied by 2. In MetaDataBuilder.java, the following code determines if a header name or value exceeds the size limit, and throws an exception if the limit is exceeded: However, no exception is thrown in the case of a negative size. Later, in Huffman.decode, the user-entered length is multiplied by 2…

Published by the source

10 Oct 2023, 21:16 UTC

Last modified by the source

16 Oct 2025, 14:25 UTC

Source last checked

26 Oct 2026, 16:40 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-wgh7-54f2-x98r

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# Patch Next advisory brief: CVE-2023-36478

Advisory: HTTP/2 HPACK integer overflow and buffer allocation
IDs: CVE-2023-36478, GHSA-wgh7-54f2-x98r
Record: https://patchnext.com/advisories/cve-2023-36478 (revision 1, source checked 26 Oct 2026, 16:40 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.eclipse.jetty.http3:http3-qpack 11.0.16, 10.0.16; org.eclipse.jetty.http2:http2-hpack 11.0.16, 10.0.16, 9.4.53. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.eclipse.jetty.http3:http3-qpack: affected >= 10.0.0, <= 10.0.15; >= 11.0.0, <= 11.0.15; fixed in 10.0.16, 11.0.16
- Maven org.eclipse.jetty.http2:http2-hpack: affected >= 10.0.0, <= 10.0.15; >= 11.0.0, <= 11.0.15; >= 9.3.0, <= 9.4.52; fixed in 10.0.16, 9.4.53, 11.0.16

## Suggested inspection (read-only)
- Maven org.eclipse.jetty.http3:http3-qpack: check the installed version with your package manager.
- Maven org.eclipse.jetty.http2:http2-hpack: 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 org.eclipse.jetty.http3:http3-qpack, org.eclipse.jetty.http2:http2-hpack.
- 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-wgh7-54f2-x98r (GitHub-reviewed advisory GHSA-wgh7-54f2-x98r lists affected ranges: Maven org.eclipse.jetty.http2:http2-hpack >=10.0.0 =11.0.0 =9.3.0 =10.0.0 =11.0.0 <=11.0.15)

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