Description
Varnish Cache, with HTTP/2 enabled, allows request smuggling and VCL authorization bypass via a large Content-Length header for a POST request. This affects Varnish Enterprise 6.0.x before 6.0.8r3, and Varnish Cache 5.x and 6.x before 6.5.2, 6.6.x before 6.6.1, and 6.0 LTS before 6.0.8.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 13 | varnish | 6.5.2-1 | — |
| Debian 12 | varnish | 6.5.2-1 | — |
| Debian 11 | varnish | 6.5.1-1+deb11u2 | DSA-5088-1 |
| Debian 10 | varnish | 6.1.1-1+deb10u3 | DSA-5088-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 22.04 LTS | varnish | 6.6.1-1ubuntu0.2 | USN-5474-1 |
| Ubuntu 20.04 LTS | varnish | 6.2.1-2ubuntu0.1 | USN-5474-1 |
| Ubuntu 18.04 LTS | varnish | 5.2.1-1ubuntu0.1 | USN-5474-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8 | varnish +2 | 6.0.6-2.module+el8.4.0+11921+1a6539fc.1 | RHSA-2021:2988 |
| RHEL 8 | varnish-modules | 0.15.0-5.module+el8.3.0+6843+b3b42fcc | RHSA-2021:2988 |
| RHEL 3 | rh-varnish6-varnish +3 | 6.0.8-2.el7 | RHSA-2021:2993 |
| RHEL 3 | rh-varnish6-varnish-modules | 0.15.0-7.el7 | RHSA-2021:2993 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8.2 EUS | varnish +2 | 6.0.2-2.module+el8.2.0+11973+a748eca7 | RHSA-2021:2988 |
| RHEL 8.2 EUS | varnish-modules | 0.15.0-4.module+el8+2481+4078e9d2 | RHSA-2021:2988 |
| RHEL 8.1 EUS | varnish +2 | 6.0.2-2.module+el8.1.0+11974+ea5ba4f1 | RHSA-2021:2988 |
| RHEL 8.1 EUS | varnish-modules | 0.15.0-4.module+el8+2481+4078e9d2 | RHSA-2021:2988 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 8 | varnish | 6.0.6-2.module+el8.3.0+179+20b582cc | RLSA-2021:2988 |
| Rocky Linux 8 | varnish-modules | 0.15.0-5.module+el8.3.0+179+20b582cc | RLSA-2021:2988 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SUSE Package Hub 15 SP3 | varnish | 7.1.0-bp153.2.3.1 | openSUSE-SU-2022:0148-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 15.3 | varnish | 7.1.0-bp153.2.3.1 | openSUSE-SU-2022:0148-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | varnish | 6.6.1-r0 | — |
| Alpine v3.23 | varnish | 6.6.1-r0 | — |
| Alpine v3.22 | varnish | 6.6.1-r0 | — |
| Alpine v3.21 | varnish | 6.6.1-r0 | — |
| Alpine v3.20 | varnish | 6.6.1-r0 | — |
Show 9 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | varnish | 6.6.1-r0 | — |
| Alpine v3.18 | varnish | 6.6.1-r0 | — |
| Alpine v3.17 | varnish | 6.6.1-r0 | — |
| Alpine v3.16 | varnish | 6.6.1-r0 | — |
| Alpine v3.15 | varnish | 6.6.1-r0 | — |
| Alpine v3.14 | varnish | 6.6.1-r0 | — |
| Alpine v3.13 | varnish | 6.5.2-r0 | — |
| Alpine v3.12 | varnish | 6.5.2-r0 | — |
| Alpine v3.11 | varnish | 6.5.2-r0 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 8 | varnish +2 | 6.0.6-2.module+el8.4.0+20258+f99218b2.1 | ELSA-2021-2988 |
| Oracle Linux 8 | varnish-modules | 0.15.0-5.module+el8.3.0+7653+45014445 | ELSA-2021-2988 |
Advisories 7
- RHSA-2021:2993 Red Hat Security Advisory: rh-varnish6-varnish security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2021:2988 Red Hat Security Advisory: varnish:6 security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- USN-5474-1 varnish vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- DSA-5088-1 varnish - security update Debian Security (DSA / DLA) · Mar 9, 2026
- RLSA-2021:2988 Important: varnish:6 security update Rocky Linux Security Advisories · Feb 4, 2026
- openSUSE-SU-2022:0148-1 Security update for varnish SUSE / openSUSE Security Updates · Feb 4, 2026
- ELSA-2021-2988 Important: varnish:6 security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Aug 3, 2021
References
- https://varnish-cache.org/security/VSV00007.html
- https://docs.varnish-software.com/security/VSV00007/
- https://github.com/varnishcache/varnish-cache/commit/9be22198e258d0e7a5c41f4291792214a29405cf
- https://github.com/varnishcache/varnish-cache/commit/82b0a629f60136e76112c6f2c6372cce77b683be
- FEDORA-2021-36e10d3f9f vendor-advisory
- FEDORA-2021-cf7585f0ca vendor-advisory
- DSA-5088 vendor-advisory