Security readout for executives and security teams
CVE-2021-33620 is a denial-of-service flaw in Squid. A remote web server can send an HTTP response that causes affected Squid proxies to lose availability for all clients. The trigger involves a header that may appear in normal HTTP traffic, so impact is operational rather than data theft. Exposure is likely where Squid is deployed as a forward proxy, cache, or gateway and processes HTTP responses from remote servers. The provided CVE data lacks CPE entries, so teams should rely on package inventories and Squid version checks. Treat this as a moderate operational risk. It does not indicate data compromise, but it can disrupt internet access or proxy-dependent services for many users. Patch during the next normal security maintenance window, sooner for central or internet-facing proxy infrastructure. Mitigation focus: Upgrade Squid to 4.15, 5.0.6, or a later fixed release.; Apply Debian, Fedora, or other distribution security updates for Squid packages.; Prioritize proxies serving many users or critical egress paths..
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
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ATT&CK lookup starting points
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CVE-2021-33620 mapping review
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Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AC:L/AV:N/A:H/C:N/I:N/PR:L/S:U/UI:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AC:L/AV:N/A:H/C:N/I:N/PR:L/S:U/UI:N2.83.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.5MediumVector: CVSS:3.1/AC:L/AV:N/A:H/C:N/I:N/PR:L/S:U/UI:N
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/squid-cache/squid/security/advisories/GHSA-572g-rvwr-6c7fCVE reference
- FEDORA-2021-c0bec55ec7CVE reference · vendor-advisory
- FEDORA-2021-24af72ff2cCVE reference · vendor-advisory
- [debian-lts-announce] 20210614 [SECURITY] [DLA 2685-1] squid3 security updateCVE reference · mailing-list
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.