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TI-2021-14866 Aliases CVE-2021-36740GHSA-8vxj-gx32-j925

Varnish Cache, with HTTP/2 enabled, allows request smuggling and VCL authorization bypass…

Priority LOW 32CWE-444Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
Low · Low · None
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.

Summary

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.

Why it matters now

EPSS 0.01599 75th percentileScored 2026-11-07
Fix Fixed Red Hat: 2 advisories

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
——all versions—No fix listedCNA
  • — Vendor— Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 10

CPEVersionsRoleVendor
cpe:2.3:a:varnish-cache:varnish_cache:*:*:*:*:plus:*:*:*6.0.0 to before 6.0.8VulnerableVarnish-cache
cpe:2.3:a:varnish-cache:varnish_cache:6.0.8:r1:*:*:plus:*:*:*6.0.8 r1VulnerableVarnish-cache
cpe:2.3:a:varnish-cache:varnish_cache:6.0.8:r2:*:*:plus:*:*:*6.0.8 r2VulnerableVarnish-cache
cpe:2.3:a:varnish-software:varnish_cache:*:*:*:*:*:*:*:*6.0.0 – 6.0.5Vulnerablevarnish-software
cpe:2.3:a:varnish-software:varnish_cache:*:*:*:*:lts:*:*:*6.0.0 – 6.0.7Vulnerablevarnish-software
cpe:2.3:a:varnish_cache_project:varnish_cache:*:*:*:*:*:*:*:*5.0.0 – 5.2.1; 6.1.0 – 6.6.0VulnerableVarnish Cache Project
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*33VulnerableFedoraproject
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*34VulnerableFedoraproject
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*10.0VulnerableDebian
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*11.0VulnerableDebian
  • cpe:2.3:a:varnish-cache:varnish_cache:*:*:*:*:plus:*:*:* Versions 6.0.0 to before 6.0.8 Vulnerable ·Varnish-cache
  • cpe:2.3:a:varnish-cache:varnish_cache:6.0.8:r1:*:*:plus:*:*:* Versions 6.0.8 r1 Vulnerable ·Varnish-cache
  • cpe:2.3:a:varnish-cache:varnish_cache:6.0.8:r2:*:*:plus:*:*:* Versions 6.0.8 r2 Vulnerable ·Varnish-cache
  • cpe:2.3:a:varnish-software:varnish_cache:*:*:*:*:*:*:*:* Versions 6.0.0 – 6.0.5 Vulnerable ·varnish-software
  • cpe:2.3:a:varnish-software:varnish_cache:*:*:*:*:lts:*:*:* Versions 6.0.0 – 6.0.7 Vulnerable ·varnish-software
  • cpe:2.3:a:varnish_cache_project:varnish_cache:*:*:*:*:*:*:*:* Versions 5.0.0 – 5.2.1; 6.1.0 – 6.6.0 Vulnerable ·Varnish Cache Project
  • cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* Versions 33 Vulnerable ·Fedoraproject
  • cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* Versions 34 Vulnerable ·Fedoraproject
  • cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* Versions 10.0 Vulnerable ·Debian
  • cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* Versions 11.0 Vulnerable ·Debian

Remediation

Red Hat 2 advisories

  • RHSA-2021:2993 Released 2021-08-03 · Red Hat rating Important
    rh-varnish6-varnish security update
    • Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7) rh-varnish6-varnish-6.0.8-2.el7, rh-varnish6-varnish-devel-6.0.8-2.el7, rh-varnish6-varnish-docs-6.0.8-2.el7 +2
    • Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.7) rh-varnish6-varnish-6.0.8-2.el7, rh-varnish6-varnish-devel-6.0.8-2.el7, rh-varnish6-varnish-docs-6.0.8-2.el7 +2
    • Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7) rh-varnish6-varnish-6.0.8-2.el7, rh-varnish6-varnish-devel-6.0.8-2.el7, rh-varnish6-varnish-docs-6.0.8-2.el7 +2
  • RHSA-2021:2988 Released 2021-08-02 · Red Hat rating Important
    varnish:6 security update
    • Red Hat Enterprise Linux AppStream (v. 8) varnish-6.0.6-2.module+el8.4.0+11921+1a6539fc.1.aarch64::varnish:6, varnish-6.0.6-2.module+el8.4.0+11921+1a6539fc.1.ppc64le::varnish:6, varnish-6.0.6-2.module+el8.4.0+11921+1a6539fc.1.s390x::varnish:6 +15
    • Red Hat Enterprise Linux AppStream EUS (v. 8.1) varnish-6.0.2-2.module+el8.1.0+11974+ea5ba4f1.aarch64::varnish:6, varnish-6.0.2-2.module+el8.1.0+11974+ea5ba4f1.ppc64le::varnish:6, varnish-6.0.2-2.module+el8.1.0+11974+ea5ba4f1.s390x::varnish:6 +15
    • Red Hat Enterprise Linux AppStream EUS (v. 8.2) varnish-6.0.2-2.module+el8.2.0+11973+a748eca7.aarch64::varnish:6, varnish-6.0.2-2.module+el8.2.0+11973+a748eca7.ppc64le::varnish:6, varnish-6.0.2-2.module+el8.2.0+11973+a748eca7.s390x::varnish:6 +15

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux AppStream (v. 8)Fixed RHSA-2021:2988
Red Hat Enterprise Linux AppStream EUS (v. 8.1)Fixed RHSA-2021:2988
Red Hat Enterprise Linux AppStream EUS (v. 8.2)Fixed RHSA-2021:2988
Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7)Fixed RHSA-2021:2993
Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.7)Fixed RHSA-2021:2993
Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7)Fixed RHSA-2021:2993
Not affected: 1 product
  • Red Hat Enterprise Linux 9

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-36740
  2. 2026-10-03 Alias added: GHSA-8vxj-gx32-j925

References

Patch 2

Advisory 5

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences