CVE-2021-33620
Squid before 4.15 and 5.x before 5.0.6 allows remote servers to cause a denial of service (affecting availability to all clients) via an HTTP response.
Does this matter?
EPSS puts the probability of exploitation in the next 30 days at 79.6%, higher than 100% of all known CVEs. Patch or mitigate before the next change window.
Description
Squid before 4.15 and 5.x before 5.0.6 allows remote servers to cause a denial of service (affecting availability to all clients) via an HTTP response. The issue trigger is a header that can be expected to exist in HTTP traffic without any malicious intent by the server.
- CVSS 3.1
- 6.5 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 79.58% probability · 100th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-20
- Affected
- squid-cache/squid · fedoraproject/fedora · debian/debian linux
- Source
- cve@mitre.org
EPSS 79.6% since 26 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- http://seclists.org/fulldisclosure/2023/Oct/14Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2023/10/11/3Mailing List, Third Party Advisory
- http://www.squid-cache.org/Versions/v4/changesets/squid-4-1e05a85bd28c22c9ca5d3ac9f5e86d6269ec0a8c.patchMailing List, Patch, Vendor Advisory
- http://www.squid-cache.org/Versions/v5/changesets/squid-5-8af775ed98bfd610f9ce762fe177e01b2675588c.patchMailing List, Patch, Vendor Advisory
- https://github.com/squid-cache/squid/security/advisories/GHSA-572g-rvwr-6c7fPatch, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2021/06/msg00014.htmlMailing List, Third Party Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LSQ3U54ZCNXR44QRPW3AV2VCS6K3TKCF/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/T4EPIWUZDJAXADDHVOPKRBTQHPBR6H66/
- http://seclists.org/fulldisclosure/2023/Oct/14Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2023/10/11/3Mailing List, Third Party Advisory
- http://www.squid-cache.org/Versions/v4/changesets/squid-4-1e05a85bd28c22c9ca5d3ac9f5e86d6269ec0a8c.patchMailing List, Patch, Vendor Advisory
- http://www.squid-cache.org/Versions/v5/changesets/squid-5-8af775ed98bfd610f9ce762fe177e01b2675588c.patchMailing List, Patch, Vendor Advisory
- https://github.com/squid-cache/squid/security/advisories/GHSA-572g-rvwr-6c7fPatch, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2021/06/msg00014.htmlMailing List, Third Party Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LSQ3U54ZCNXR44QRPW3AV2VCS6K3TKCF/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/T4EPIWUZDJAXADDHVOPKRBTQHPBR6H66/
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.