CVE-2026-56866
CVE-2026-56866 · HTTP/1 client connection desynchronization after CONNECT rejection in net/http
This page contains facts from public vulnerability sources. Check the original advisory before updating.
This page shows selected source facts. See the linked advisories for the complete description and affected versions.
When http.Transport sends an HTTP/1 CONNECT request with a non-empty Request.Body, it writes the body directly to the connection without framing after the request headers. If the server rejects the CONNECT request with a non-2xx keep-alive response, Transport returns the connection to the idle pool. Because CONNECT requests do not have a request body, the server may interpret the trailing body bytes as a subsequent pipelined HTTP/1.1 request on the connection, leaving the pooled connection desynchronized and causing the next caller that reuses it to read the response to the injected request. In reverse proxies (including httputil.ReverseProxy) that forward CONNECT requests through a shared Transport, this can lead to cross-user response poisoning.
CVSS 7.5 · High · EPSS 0.5% · Fix available
- Published
- Updated
Stack: system
Affected products and versions
net/http
- Versions
- ≥ 0, < 1.26.9: Affected (semver)
- ≥ 1.27.0-0, < 1.27.2: Affected (semver)
Update to 1.26.9; Update to 1.27.2
net/http/httputil
- Versions
- ≥ 0, < 1.26.9: Affected (semver)
- ≥ 1.27.0-0, < 1.27.2: Affected (semver)
Update to 1.26.9; Update to 1.27.2
golang-1.19 Debian:12
- Versions
- 1.19.10-1
- 1.19.10-2
- 1.19.11-1
- 1.19.12-1
- 1.19.12-2
- 1.19.12-2~bpo11+1
- 1.19.12-2~bpo12+1
- 1.19.13-1
- 1.19.13-1~bpo11+1
- 1.19.13-1~bpo12+1
- 1.19.8-2
- 1.19.9-1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
golang-1.24 Debian:13
- Versions
- 1.24.12-1
- 1.24.13-1
- 1.24.13-2
- 1.24.4-1
- 1.24.4-2
- 1.24.4-3
- 1.24.4-4
- 1.24.7-1
- 1.24.8-1
- 1.24.9-1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
golang-1.26 Debian:14
- Versions
- 1.26.0-1
- 1.26.1-1
- 1.26.2-1
- 1.26.2-2
- 1.26.2-3
- 1.26.3-1
- 1.26.3-1~bpo13+1
- 1.26.3-2
- 1.26.3-2~bpo13+1
- 1.26.4-1
- 1.26.4-1~bpo13+1
- 1.26.5-1
- 1.26.5-1~bpo13+1
- 1.26.6-1
- 1.26.6-2
- 1.26.7-1
- 1.26.7-1~bpo13+1
- 1.26.8-1
- 1.26.8-1~bpo13+1
- 1.26.8-2
- 1.26~rc2-1
- 1.26~rc3-1
- 1.26~rc3-2
- Affected ranges
- ECOSYSTEM: < 1.26.9-1
Update to 1.26.9-1
golang-1.27 Debian:14
- Versions
- 1.27.0-1
- 1.27.0-1~bpo13+1
- 1.27.1-1
- 1.27.1-2
- 1.27.1-2~bpo13+1
- 1.27~rc1-1
- 1.27~rc2-1
- 1.27~rc3-1
- Affected ranges
- ECOSYSTEM: < 1.27.2-1
Update to 1.27.2-1
golang-1.10 Ubuntu:14.04:LTS
- Versions
- 1.10.4-2ubuntu1~14.04.1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
golang-1.10 Ubuntu:16.04:LTS
- Versions
- 1.10.4-2ubuntu1~16.04.1
- 1.10.4-2ubuntu1~16.04.2
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
golang-1.6 Ubuntu:16.04:LTS
- Versions
- 1.6-0ubuntu1
- 1.6-0ubuntu2
- 1.6-0ubuntu3
- 1.6-0ubuntu4
- 1.6-0ubuntu5
- 1.6.1-0ubuntu1
- 1.6.2-0ubuntu5~16.04
- 1.6.2-0ubuntu5~16.04.2
- 1.6.2-0ubuntu5~16.04.3
- 1.6.2-0ubuntu5~16.04.4
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
golang-1.13 Ubuntu:Pro:16.04:LTS
- Versions
- 1.13.8-1ubuntu1~16.04.2
- 1.13.8-1ubuntu1~16.04.3
- 1.13.8-1ubuntu1~16.04.3+esm2
- 1.13.8-1ubuntu1~16.04.3+esm3
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
golang-1.18 Ubuntu:Pro:16.04:LTS
- Versions
- 1.18.1-1ubuntu1~16.04.6
- 1.18.1-1ubuntu1~16.04.6+esm1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
golang-1.10 Ubuntu:18.04:LTS
- Versions
- 1.10~rc1-1
- 1.10~rc1-1ubuntu1
- 1.10~rc1-2ubuntu1
- 1.10~rc2-1ubuntu1
- 1.10-1ubuntu1
- 1.10.1-1ubuntu2
- 1.10.4-2ubuntu1~18.04.1
- 1.10.4-2ubuntu1~18.04.2
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
golang-1.13 Ubuntu:Pro:18.04:LTS
- Versions
- 1.13.8-1ubuntu1~18.04.2
- 1.13.8-1ubuntu1~18.04.3
- 1.13.8-1ubuntu1~18.04.4
- 1.13.8-1ubuntu1~18.04.4+esm1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
golang-1.16 Ubuntu:Pro:18.04:LTS
- Versions
- 1.16.2-0ubuntu1~18.04.2
- 1.16.2-0ubuntu1~18.04.2+esm1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
golang-1.18 Ubuntu:Pro:18.04:LTS
- Versions
- 1.18.1-1ubuntu1~18.04.3
- 1.18.1-1ubuntu1~18.04.4
- 1.18.1-1ubuntu1~18.04.4+esm1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
golang-1.8 Ubuntu:18.04:LTS
- Versions
- 1.8.3-2ubuntu1
- 1.8.3-2ubuntu1.18.04.1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
golang-1.9 Ubuntu:18.04:LTS
- Versions
- 1.9.1-2ubuntu1
- 1.9.2-1ubuntu1
- 1.9.2-3ubuntu1
- 1.9.3-1ubuntu1
- 1.9.4-1ubuntu1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
golang-1.13 Ubuntu:20.04:LTS
- Versions
- 1.13.1-1ubuntu1
- 1.13.3-1ubuntu1
- 1.13.4-1ubuntu1
- 1.13.5-1ubuntu1
- 1.13.6-1ubuntu1
- 1.13.6-2ubuntu1
- 1.13.7-1ubuntu1
- 1.13.8-1ubuntu1
- 1.13.8-1ubuntu1.1
- 1.13.8-1ubuntu1.2
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
golang-1.14 Ubuntu:20.04:LTS
- Versions
- 1.14~beta1-1
- 1.14~beta1-2
- 1.14~rc1-1
- 1.14-1
- 1.14.1-1
- 1.14.2-1
- 1.14.2-1ubuntu1
- 1.14.3-2ubuntu2~20.04.1
- 1.14.3-2ubuntu2~20.04.2
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
golang-1.16 Ubuntu:Pro:20.04:LTS
- Versions
- 1.16.2-0ubuntu1~20.04
- 1.16.2-0ubuntu1~20.04.1
- 1.16.2-0ubuntu1~20.04.1+esm1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
golang-1.18 Ubuntu:20.04:LTS
- Versions
- 1.18.1-1ubuntu1~20.04.1
- 1.18.1-1ubuntu1~20.04.2
- 1.18.1-1ubuntu1~20.04.3
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
golang-1.20 Ubuntu:20.04:LTS
- Versions
- 1.20.3-1ubuntu0.1~20.04
- 1.20.3-1ubuntu0.1~20.04.1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
golang-1.21 Ubuntu:20.04:LTS
- Versions
- 1.21.1-1~ubuntu20.04.1
- 1.21.1-1~ubuntu20.04.2
- 1.21.1-1~ubuntu20.04.3
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
golang-1.17 Ubuntu:22.04:LTS
- Versions
- 1.17-1ubuntu2
- 1.17.3-1ubuntu1
- 1.17.3-1ubuntu2
- 1.17.13-3ubuntu1
- 1.17.13-3ubuntu1.2
- 1.17.13-3ubuntu1.3
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published