CVE-2021-36740
No known exploitation. EPSS puts it in the 76th percentile. Fixed in 6.0.8.
What to do
Find your product and version, then upgrade to the build on the right.
- Varnish-cache Varnish CacheAffected: ≥ 6.0.0, < 6.0.8Upgrade to: 6.0.8Affected: ≥ 6.0.0, ≤ 6.0.5Upgrade to: after 6.0.5Affected: ≥ 5.0.0, ≤ 5.2.1Upgrade to: after 5.2.1Stated by: NVD
Versions as the sources state them. Full version matrix after sign-in
What it is
From the CVE record
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.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
1.6% chance of exploitation activity in the next 30 days, which ranks it in the 76th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
7 events over 1807 days, from the signal feeds we watch.
- OpenVAS check added
- Patch availableworkaround available, record updated
- Publishedweakness classified, att&ck mapped
Affected products
And 1 more affected product. See all after sign-in
Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Scored 6.5 by NVD.
How it is reached
- Attack Vector NetworkExploitable remotely over the network without any special conditions
- Attack Complexity LowNo special conditions — the attack can be reliably reproduced
- Privileges Required NoneNo authentication required — anyone can exploit this
- User Interaction NoneNo user interaction needed — fully automated exploitation
Scope
- Scope UnchangedImpact is limited to the vulnerable component itself
Impact if exploited
- Confidentiality LowSome restricted information is disclosed, but limited in scope
- Integrity LowData modification is possible but limited in scope or consequence
- Availability NoneNo availability impact
Weaknesses
ATT&CK techniques
Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.
Sources
References in the record
- varnish-cache.org/security/VSV00007.html
- docs.varnish-software.com/security/VSV00007/
- github.com/varnishcache/varnish-cache/commit/9be22198e258d0e7a5c41f4291792214a29405cf
And 4 more references. See all after sign-in
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