# CVE-2026-78663: Double flow control refund on HTTP/2 server streams in net/http

CVE-2026-78663 is fixed in 35 products on 1 platform, first by DEBIAN-CVE-2026-78663, released October 12, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-78663
- Priority: High
- CVSS: 9.1 (Important)
- EPSS: 0.0086
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 8, 2026
- Weakness: Multiple Operations on Resource in Single-Operation Context
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-78663

## Description

The HTTP/2 server can refund connection-level flow control twice for the same data: Once when a client resets a stream (refunding data for any sent-but-unread portion of the stream), and again when a request handler reads the buffered data. A malicious client can exploit this to bypass the configured connection-level flow control limit (MaxReceiveBufferPerConnection). Total buffered data is still limited by the concurrent stream limit and stream-level flow control.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | amazon-cloudwatch-agent amzn 2023 | 1.300073.2-1.amzn2023 | [ALAS2023-2026-3350](https://patchblox.com/security/data/fix/linux/alas2023-2026-3350.md) | Nov 7, 2026 |
| Linux | amazon-ecr-credential-helper amzn 2023 | 0.12.0-5.amzn2023 | [ALAS2023-2026-3271](https://patchblox.com/security/data/fix/linux/alas2023-2026-3271.md) | Nov 7, 2026 |
| Linux | cadvisor opensuse-leap 16.0 | 0.60.6-bp160.4.1 | [OPENSUSE-SU-2026:22218-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22218-1.md) | Nov 7, 2026 |
| Linux | containerd amzn 2023 | 2.3.7-1.amzn2023.0.1 | [ALAS2023-2026-3273](https://patchblox.com/security/data/fix/linux/alas2023-2026-3273.md) | Nov 7, 2026 |
| Linux | containerd-debuginfo amzn 2023 | 2.3.7-1.amzn2023.0.1 | [ALAS2023-2026-3273](https://patchblox.com/security/data/fix/linux/alas2023-2026-3273.md) | Nov 7, 2026 |
| Linux | containerd-debugsource amzn 2023 | 2.3.7-1.amzn2023.0.1 | [ALAS2023-2026-3273](https://patchblox.com/security/data/fix/linux/alas2023-2026-3273.md) | Nov 7, 2026 |
| Linux | containerd-stress amzn 2023 | 2.3.7-1.amzn2023.0.1 | [ALAS2023-2026-3273](https://patchblox.com/security/data/fix/linux/alas2023-2026-3273.md) | Nov 7, 2026 |
| Linux | containerd-stress-debuginfo amzn 2023 | 2.3.7-1.amzn2023.0.1 | [ALAS2023-2026-3273](https://patchblox.com/security/data/fix/linux/alas2023-2026-3273.md) | Nov 7, 2026 |
| Linux | credentials-fetcher amzn 2023 | 2.0.3-1.amzn2023.0.7 | [ALAS2023-2026-3228](https://patchblox.com/security/data/fix/linux/alas2023-2026-3228.md) | Nov 7, 2026 |
| Linux | delve RHEL 8 | 0:1.26.1-1.module+el8.10.0+24516+40554724 | [RHSA-2026:86203](https://patchblox.com/security/data/fix/linux/rhsa-2026-86203.md) | Oct 21, 2026 |
| Linux | delve almalinux 8 | 1.26.1-1.module_el8.10.0+4307+6e4cbc60 | [ALSA-2026:86203](https://patchblox.com/security/data/fix/linux/alsa-2026-86203.md) | Nov 7, 2026 |
| Linux | go-toolset RHEL 8 | 0:1.26.10-1.module+el8.10.0+25107+6b50279c | [RHSA-2026:86203](https://patchblox.com/security/data/fix/linux/rhsa-2026-86203.md) | Oct 21, 2026 |
| Linux | go-toolset RHEL 9 | 0:1.26.10-1.el9_8 | [RHSA-2026:86196](https://patchblox.com/security/data/fix/linux/rhsa-2026-86196.md) | Oct 21, 2026 |
| Linux | go-toolset almalinux 10 | 1.26.10-1.el10_2.alma.1 | [ALSA-2026:86093](https://patchblox.com/security/data/fix/linux/alsa-2026-86093.md) | Nov 7, 2026 |
| Linux | go-toolset almalinux 8 | 1.26.10-1.module_el8.10.0+4307+6e4cbc60 | [ALSA-2026:86203](https://patchblox.com/security/data/fix/linux/alsa-2026-86203.md) | Nov 7, 2026 |
| Linux | go-toolset almalinux 9 | 1.26.10-1.el9_8 | [ALSA-2026:86196](https://patchblox.com/security/data/fix/linux/alsa-2026-86196.md) | Nov 7, 2026 |
| Linux | go1.26 opensuse-leap 16.0 | 1.26.10-160000.1.1 | [OPENSUSE-SU-2026:22152-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22152-1.md) | Nov 7, 2026 |
| Linux | go1.26 sles 15.6 | 1.26.10-150000.1.36.1 | [SUSE-SU-2026:4864-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4864-1.md) | Nov 7, 2026 |
| Linux | go1.26 sles 15.7 | 1.26.10-150000.1.36.1 | [SUSE-SU-2026:4864-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4864-1.md) | Nov 7, 2026 |
| Linux | go1.26 sles 16.0 | 1.26.10-160000.1.1 | [SUSE-SU-2026:24359-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24359-1.md) | Nov 7, 2026 |
| Linux | go1.26-openssl sles 15.6 | 1.26.10-150600.13.18.1 | [SUSE-SU-2026:4866-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4866-1.md) | Nov 7, 2026 |
| Linux | go1.26-openssl sles 15.7 | 1.26.10-150600.13.18.1 | [SUSE-SU-2026:4866-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4866-1.md) | Nov 7, 2026 |
| Linux | go1.27 opensuse-leap 16.0 | 1.27.2-160000.1.1 | [OPENSUSE-SU-2026:22093-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22093-1.md) | Nov 7, 2026 |
| Linux | go1.27 sles 15.6 | 1.27.2-150000.1.12.1 | [SUSE-SU-2026:4625-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4625-1.md) | Nov 7, 2026 |
| Linux | go1.27 sles 15.7 | 1.27.2-150000.1.12.1 | [SUSE-SU-2026:4625-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4625-1.md) | Nov 7, 2026 |
| Linux | go1.27 sles 16.0 | 1.27.2-160000.1.1 | [SUSE-SU-2026:24237-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24237-1.md) | Nov 7, 2026 |
| Linux | golang RHEL 10 | 1.26.10-1.el10_0 | [RHSA-2026:87040](https://patchblox.com/security/data/fix/linux/rhsa-2026-87040.md) | Oct 21, 2026 |
| Linux | golang RHEL 8 | 0:1.26.10-1.module+el8.10.0+25107+6b50279c | [RHSA-2026:86203](https://patchblox.com/security/data/fix/linux/rhsa-2026-86203.md) | Oct 21, 2026 |
| Linux | golang RHEL 9 | 0:1.26.10-1.el9_8 | [RHSA-2026:86196](https://patchblox.com/security/data/fix/linux/rhsa-2026-86196.md) | Oct 21, 2026 |
| Linux | golang almalinux 10 | 1.26.10-1.el10_2.alma.1 | [ALSA-2026:86093](https://patchblox.com/security/data/fix/linux/alsa-2026-86093.md) | Nov 7, 2026 |
| Linux | golang almalinux 8 | 1.26.10-1.module_el8.10.0+4307+6e4cbc60 | [ALSA-2026:86203](https://patchblox.com/security/data/fix/linux/alsa-2026-86203.md) | Nov 7, 2026 |
| Linux | golang almalinux 9 | 1.26.10-1.el9_8 | [ALSA-2026:86196](https://patchblox.com/security/data/fix/linux/alsa-2026-86196.md) | Nov 7, 2026 |
| Linux | golang amzn 2023 | 1.26.9-1.amzn2023.0.1 | [ALAS2023-2026-3225](https://patchblox.com/security/data/fix/linux/alas2023-2026-3225.md) | Nov 7, 2026 |
| Linux | golang-1.22 Ubuntu 22.04.1 LTS (jammy) | 1.22.2-2~22.04.4 | [golang-1.22 1.22.2-2~22.04.4](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-golang-1.22-1.22.2-2-22.04.4.md) | Oct 20, 2026 |
| Linux | golang-1.22 Ubuntu 24.04.5 LTS (noble) | 1.22.2-2ubuntu0.5 | [golang-1.22 1.22.2-2ubuntu0.5](https://patchblox.com/security/data/fix/linux/ubuntu-noble-golang-1.22-1.22.2-2ubuntu0.5.md) | Oct 20, 2026 |
| Linux | golang-1.22-go Ubuntu 22.04.1 LTS (jammy) | 1.22.2-2~22.04.4 | [golang-1.22-go 1.22.2-2~22.04.4](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-golang-1.22-go-1.22.2-2-22.04.4.md) | Oct 20, 2026 |
| Linux | golang-1.22-go Ubuntu 24.04.5 LTS (noble) | 1.22.2-2ubuntu0.5 | [golang-1.22-go 1.22.2-2ubuntu0.5](https://patchblox.com/security/data/fix/linux/ubuntu-noble-golang-1.22-go-1.22.2-2ubuntu0.5.md) | Oct 20, 2026 |
| Linux | golang-1.22-src Ubuntu 22.04.1 LTS (jammy) | 1.22.2-2~22.04.4 | [golang-1.22-src 1.22.2-2~22.04.4](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-golang-1.22-src-1.22.2-2-22.04.4.md) | Oct 20, 2026 |
| Linux | golang-1.22-src Ubuntu 24.04.5 LTS (noble) | 1.22.2-2ubuntu0.5 | [golang-1.22-src 1.22.2-2ubuntu0.5](https://patchblox.com/security/data/fix/linux/ubuntu-noble-golang-1.22-src-1.22.2-2ubuntu0.5.md) | Oct 20, 2026 |
| Linux | golang-1.26 Debian 14 | 1.26.9-1 | [DEBIAN-CVE-2026-78663](https://patchblox.com/security/data/fix/linux/debian-cve-2026-78663.md) | Oct 12, 2026 |
| Linux | golang-1.27 Debian 14 | 1.27.2-1 | [DEBIAN-CVE-2026-78663](https://patchblox.com/security/data/fix/linux/debian-cve-2026-78663.md) | Oct 12, 2026 |
| Linux | golang-bin RHEL 8 | 0:1.26.10-1.module+el8.10.0+25107+6b50279c | [RHSA-2026:86203](https://patchblox.com/security/data/fix/linux/rhsa-2026-86203.md) | Oct 21, 2026 |
| Linux | golang-bin RHEL 9 | 0:1.26.10-1.el9_8 | [RHSA-2026:86196](https://patchblox.com/security/data/fix/linux/rhsa-2026-86196.md) | Oct 21, 2026 |
| Linux | golang-bin almalinux 10 | 1.26.10-1.el10_2.alma.1 | [ALSA-2026:86093](https://patchblox.com/security/data/fix/linux/alsa-2026-86093.md) | Nov 7, 2026 |
| Linux | golang-bin almalinux 8 | 1.26.10-1.module_el8.10.0+4307+6e4cbc60 | [ALSA-2026:86203](https://patchblox.com/security/data/fix/linux/alsa-2026-86203.md) | Nov 7, 2026 |
| Linux | golang-bin almalinux 9 | 1.26.10-1.el9_8 | [ALSA-2026:86196](https://patchblox.com/security/data/fix/linux/alsa-2026-86196.md) | Nov 7, 2026 |
| Linux | golang-bin amzn 2023 | 1.26.9-1.amzn2023.0.1 | [ALAS2023-2026-3225](https://patchblox.com/security/data/fix/linux/alas2023-2026-3225.md) | Nov 7, 2026 |
| Linux | golang-docs RHEL 8 | 0:1.26.10-1.module+el8.10.0+25107+6b50279c | [RHSA-2026:86203](https://patchblox.com/security/data/fix/linux/rhsa-2026-86203.md) | Oct 21, 2026 |
| Linux | golang-docs RHEL 9 | 0:1.26.10-1.el9_8 | [RHSA-2026:86196](https://patchblox.com/security/data/fix/linux/rhsa-2026-86196.md) | Oct 21, 2026 |
| Linux | golang-docs almalinux 10 | 1.26.10-1.el10_2.alma.1 | [ALSA-2026:86093](https://patchblox.com/security/data/fix/linux/alsa-2026-86093.md) | Nov 7, 2026 |
| Linux | golang-docs almalinux 8 | 1.26.10-1.module_el8.10.0+4307+6e4cbc60 | [ALSA-2026:86203](https://patchblox.com/security/data/fix/linux/alsa-2026-86203.md) | Nov 7, 2026 |
| Linux | golang-docs almalinux 9 | 1.26.10-1.el9_8 | [ALSA-2026:86196](https://patchblox.com/security/data/fix/linux/alsa-2026-86196.md) | Nov 7, 2026 |
| Linux | golang-docs amzn 2023 | 1.26.9-1.amzn2023.0.1 | [ALAS2023-2026-3225](https://patchblox.com/security/data/fix/linux/alas2023-2026-3225.md) | Nov 7, 2026 |
| Linux | golang-golang-x-net Debian 14 | 1:0.60.0-1 | [DEBIAN-CVE-2026-78663](https://patchblox.com/security/data/fix/linux/debian-cve-2026-78663.md) | Oct 12, 2026 |
| Linux | golang-misc RHEL 8 | 0:1.26.10-1.module+el8.10.0+25107+6b50279c | [RHSA-2026:86203](https://patchblox.com/security/data/fix/linux/rhsa-2026-86203.md) | Oct 21, 2026 |
| Linux | golang-misc RHEL 9 | 0:1.26.10-1.el9_8 | [RHSA-2026:86196](https://patchblox.com/security/data/fix/linux/rhsa-2026-86196.md) | Oct 21, 2026 |
| Linux | golang-misc almalinux 10 | 1.26.10-1.el10_2.alma.1 | [ALSA-2026:86093](https://patchblox.com/security/data/fix/linux/alsa-2026-86093.md) | Nov 7, 2026 |
| Linux | golang-misc almalinux 8 | 1.26.10-1.module_el8.10.0+4307+6e4cbc60 | [ALSA-2026:86203](https://patchblox.com/security/data/fix/linux/alsa-2026-86203.md) | Nov 7, 2026 |
| Linux | golang-misc almalinux 9 | 1.26.10-1.el9_8 | [ALSA-2026:86196](https://patchblox.com/security/data/fix/linux/alsa-2026-86196.md) | Nov 7, 2026 |
| Linux | golang-misc amzn 2023 | 1.26.9-1.amzn2023.0.1 | [ALAS2023-2026-3225](https://patchblox.com/security/data/fix/linux/alas2023-2026-3225.md) | Nov 7, 2026 |
| Linux | golang-race RHEL 8 | 0:1.26.10-1.module+el8.10.0+25107+6b50279c | [RHSA-2026:86203](https://patchblox.com/security/data/fix/linux/rhsa-2026-86203.md) | Oct 21, 2026 |
| Linux | golang-race RHEL 9 | 0:1.26.10-1.el9_8 | [RHSA-2026:86196](https://patchblox.com/security/data/fix/linux/rhsa-2026-86196.md) | Oct 21, 2026 |
| Linux | golang-race almalinux 10 | 1.26.10-1.el10_2.alma.1 | [ALSA-2026:86093](https://patchblox.com/security/data/fix/linux/alsa-2026-86093.md) | Nov 7, 2026 |
| Linux | golang-race almalinux 8 | 1.26.10-1.module_el8.10.0+4307+6e4cbc60 | [ALSA-2026:86203](https://patchblox.com/security/data/fix/linux/alsa-2026-86203.md) | Nov 7, 2026 |
| Linux | golang-race almalinux 9 | 1.26.10-1.el9_8 | [ALSA-2026:86196](https://patchblox.com/security/data/fix/linux/alsa-2026-86196.md) | Nov 7, 2026 |
| Linux | golang-shared amzn 2023 | 1.26.9-1.amzn2023.0.1 | [ALAS2023-2026-3225](https://patchblox.com/security/data/fix/linux/alas2023-2026-3225.md) | Nov 7, 2026 |
| Linux | golang-src RHEL 8 | 0:1.26.10-1.module+el8.10.0+25107+6b50279c | [RHSA-2026:86203](https://patchblox.com/security/data/fix/linux/rhsa-2026-86203.md) | Oct 21, 2026 |
| Linux | golang-src RHEL 9 | 0:1.26.10-1.el9_8 | [RHSA-2026:86196](https://patchblox.com/security/data/fix/linux/rhsa-2026-86196.md) | Oct 21, 2026 |
| Linux | golang-src almalinux 10 | 1.26.10-1.el10_2.alma.1 | [ALSA-2026:86093](https://patchblox.com/security/data/fix/linux/alsa-2026-86093.md) | Nov 7, 2026 |
| Linux | golang-src almalinux 8 | 1.26.10-1.module_el8.10.0+4307+6e4cbc60 | [ALSA-2026:86203](https://patchblox.com/security/data/fix/linux/alsa-2026-86203.md) | Nov 7, 2026 |
| Linux | golang-src almalinux 9 | 1.26.10-1.el9_8 | [ALSA-2026:86196](https://patchblox.com/security/data/fix/linux/alsa-2026-86196.md) | Nov 7, 2026 |
| Linux | golang-src amzn 2023 | 1.26.9-1.amzn2023.0.1 | [ALAS2023-2026-3225](https://patchblox.com/security/data/fix/linux/alas2023-2026-3225.md) | Nov 7, 2026 |
| Linux | golang-tests RHEL 8 | 0:1.26.10-1.module+el8.10.0+25107+6b50279c | [RHSA-2026:86203](https://patchblox.com/security/data/fix/linux/rhsa-2026-86203.md) | Oct 21, 2026 |
| Linux | golang-tests RHEL 9 | 0:1.26.10-1.el9_8 | [RHSA-2026:86196](https://patchblox.com/security/data/fix/linux/rhsa-2026-86196.md) | Oct 21, 2026 |
| Linux | golang-tests almalinux 10 | 1.26.10-1.el10_2.alma.1 | [ALSA-2026:86093](https://patchblox.com/security/data/fix/linux/alsa-2026-86093.md) | Nov 7, 2026 |
| Linux | golang-tests almalinux 8 | 1.26.10-1.module_el8.10.0+4307+6e4cbc60 | [ALSA-2026:86203](https://patchblox.com/security/data/fix/linux/alsa-2026-86203.md) | Nov 7, 2026 |
| Linux | golang-tests almalinux 9 | 1.26.10-1.el9_8 | [ALSA-2026:86196](https://patchblox.com/security/data/fix/linux/alsa-2026-86196.md) | Nov 7, 2026 |
| Linux | golang-tests amzn 2023 | 1.26.9-1.amzn2023.0.1 | [ALAS2023-2026-3225](https://patchblox.com/security/data/fix/linux/alas2023-2026-3225.md) | Nov 7, 2026 |
| Linux | google-cloud-sap-agent sles 16.0 | 3.15-160000.5.1 | [SUSE-SU-2026:24604-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24604-1.md) | Nov 8, 2026 |
| Linux | kubevirt1.9 opensuse-leap 16.0 | 1.9.1-160000.1.1 | [OPENSUSE-SU-2026:22180-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22180-1.md) | Nov 7, 2026 |
| Linux | nerdctl amzn 2023 | 2.3.5-1.amzn2023.0.2 | [ALAS2023-2026-3274](https://patchblox.com/security/data/fix/linux/alas2023-2026-3274.md) | Nov 7, 2026 |
| Linux | oci-add-hooks amzn 2023 | 0-0.1.20200504git268e3bb.amzn2023.0.13 | [ALAS2023-2026-3272](https://patchblox.com/security/data/fix/linux/alas2023-2026-3272.md) | Nov 7, 2026 |
| Linux | oci-add-hooks-debuginfo amzn 2023 | 0-0.1.20200504git268e3bb.amzn2023.0.13 | [ALAS2023-2026-3272](https://patchblox.com/security/data/fix/linux/alas2023-2026-3272.md) | Nov 7, 2026 |
| Linux | oci-add-hooks-debugsource amzn 2023 | 0-0.1.20200504git268e3bb.amzn2023.0.13 | [ALAS2023-2026-3272](https://patchblox.com/security/data/fix/linux/alas2023-2026-3272.md) | Nov 7, 2026 |
| Linux | soci-snapshotter amzn 2023 | 0.16.0-1.amzn2023.0.2 | [ALAS2023-2026-3270](https://patchblox.com/security/data/fix/linux/alas2023-2026-3270.md) | Nov 7, 2026 |

---

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