Vulnerability Name:

CVE-2021-28543 (CCN-198292)

Assigned:2021-03-16
Published:2021-03-16
Updated:2022-06-28
Summary:Varnish varnish-modules before 0.17.1 allows remote attackers to cause a denial of service (daemon restart) in some configurations. This does not affect organizations that only install the Varnish Cache product; however, it is common to install both Varnish Cache and varnish-modules. Specifically, an assertion failure or NULL pointer dereference can be triggered in Varnish Cache through the varnish-modules header.append() and header.copy() functions. For some Varnish Configuration Language (VCL) files, this gives remote clients an opportunity to cause a Varnish Cache restart. A restart reduces overall availability and performance due to an increased number of cache misses, and may cause higher load on backend servers.
CVSS v3 Severity:7.5 High (CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
6.5 Medium (Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope:Scope (S): Unchanged
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): High
5.3 Medium (CCN CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)
4.6 Medium (CCN Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope:Scope (S): Unchanged
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): Low
CVSS v2 Severity:5.0 Medium (CVSS v2 Vector: AV:N/AC:L/Au:N/C:N/I:N/A:P)
Exploitability Metrics:Access Vector (AV): Network
Access Complexity (AC): Low
Authentication (Au): None
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): Partial
5.0 Medium (CCN CVSS v2 Vector: AV:N/AC:L/Au:N/C:N/I:N/A:P)
Exploitability Metrics:Access Vector (AV): Network
Access Complexity (AC): Low
Athentication (Au): None
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): Partial
Vulnerability Type:CWE-476
CWE-617
Vulnerability Consequences:Denial of Service
References:Source: MITRE
Type: CNA
CVE-2021-28543

Source: XF
Type: UNKNOWN
varnishcache-cve202128543-dos(198292)

Source: FEDORA
Type: Mailing List, Third Party Advisory
FEDORA-2021-2ad352ec70

Source: CCN
Type: Varnish Cache VSV00006
varnish-modules Denial of Service

Source: MISC
Type: Vendor Advisory
https://varnish-cache.org/security/VSV00006.html

Vulnerable Configuration:Configuration 1:
  • cpe:/a:varnish-cache:varnish-modules:*:*:*:*:*:*:*:* (Version < 0.17.1)
  • OR cpe:/a:varnish-cache:varnish-modules_klarlack:*:*:*:*:*:*:*:* (Version < 0.17.1)

  • Configuration 2:
  • cpe:/o:fedoraproject:fedora:34:*:*:*:*:*:*:*

  • * Denotes that component is vulnerable
    BACK
    varnish-cache varnish-modules *
    varnish-cache varnish-modules klarlack *
    fedoraproject fedora 34