Home/CVE/Varnish Cache, with HTTP/2 enabled, allows request smuggling and VCL authorization bypass via a large Content-Length hea
CVE

CVE-2021-36740

Varnish Cache, with HTTP/2 enabled, allows request smuggling and VCL authorization bypass via a large Content-Length hea

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.

MEDIUM · CVSS 6.5 EPSS 0.00957
Monitor
  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
▤

Affected Products & Versions

8
varnish-cache varnish cache>= 6.0.0 and < 6.0.8
varnish-cache varnish cacheall versions
varnish-software varnish cache>= 6.0.0 and <= 6.0.5
varnish-software varnish cache>= 6.0.0 and <= 6.0.7
varnish cache project varnish cache>= 5.0.0 and <= 5.2.1
varnish cache project varnish cache>= 6.1.0 and <= 6.6.0
fedoraproject fedoraall versions
debian linuxall versions
▣

Scoring & Timeline

6.5
MEDIUM · CVSS v3.1 · cve@mitre.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD14 Jul 2021 · 05:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
⚑

Vendor Advisories

4
usnUSN-5474-1
suse-csafopenSUSE-SU-2022:0148-1
rhsaRHSA-2021:2988Important
rhsaRHSA-2021:2993Important
🔗

References & Sources

7
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://docs.varnish-software.com/security/VSV00007/MitigationVendor Advisory
https://github.com/varnishcache/varnish-cache/commit/82b0a629f60136e76112c6f2c6372cce77b683bePatchThird Party Advisory
https://github.com/varnishcache/varnish-cache/commit/9be22198e258d0e7a5c41f4291792214a29405cfPatchThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/THV2DQA2GS65HUCKK4KSD2XLN3AAQ2V5/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZHBNLDEOTGYRIEQZBWV7F6VPYS4O2AAK/
https://varnish-cache.org/security/VSV00007.htmlMitigationVendor Advisory
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