CVE-2021-36740
MEDIUM
6.5
CVSS Score
Published: July 14, 2021 at 04:07 PM UTC
Updated: June 17, 2026 at 03:59 AM UTC
5 products affected across 5 vendorsDebian LinuxFedoraVarnish Cache
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Severity
MEDIUM6.5
Exploit prediction
EPSS 2%
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.
Affected
Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.
Debian Linux· Debiandrupal
95%5.0.0 ≤ v ≤ 5.2.16.1.0 ≤ v ≤ 6.6.0
Affected range stops below 6.0.8, so it looks safe — our inference, not a vendor statement
6.0.0 ≤ v ≤ 6.0.56.0.0 ≤ v ≤ 6.0.7
Remediation
No guide yetNo remediation guidance has been written for this CVE yet. What the record does show:
Patch and advisory references
- https://docs.varnish-software.com/security/VSV00007/
- https://github.com/varnishcache/varnish-cache/commit/82b0a629f60136e76112c6f2c6372cce77b683be
- https://github.com/varnishcache/varnish-cache/commit/9be22198e258d0e7a5c41f4291792214a29405cf
- 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/
References (7)
x_refsource_MISCMitigationVendor Advisory
Source: [email protected]
https://docs.varnish-software.com/security/VSV00007/x_refsource_MISCPatchThird Party Advisory
Source: [email protected]
https://github.com/varnishcache/varnish-cache/commit/82b0a629f60136e76112c6f2c6372cce77b683bex_refsource_MISCPatchThird Party Advisory
Source: [email protected]
https://github.com/varnishcache/varnish-cache/commit/9be22198e258d0e7a5c41f4291792214a29405cfVendor Advisoryx_refsource_FEDORA
Source: [email protected]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/THV2DQA2GS65HUCKK4KSD2XLN3AAQ2V5/Vendor Advisoryx_refsource_FEDORA
Source: [email protected]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZHBNLDEOTGYRIEQZBWV7F6VPYS4O2AAK/x_refsource_MISCMitigationVendor Advisory
Source: [email protected]
https://varnish-cache.org/security/VSV00007.htmlVendor Advisoryx_refsource_DEBIANThird Party Advisory
Source: [email protected]
https://www.debian.org/security/2022/dsa-5088CVSS
- Attack Vector
- NETWORK
- Complexity
- LOW
- Privileges
- NONE
- User Interaction
- NONE
- Scope
- UNCHANGED
- Confidentiality
- LOW
- Integrity
- LOW
- Availability
- NONE
Vector?
Quick Info
StatusMODIFIED
CWE
CWE-444
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