CVE-2019-12520An issue was discovered in Squid through 4.7 and 5. When receiving a request, Squid checks its cache to see if it can serve up a response.…
- 7.5HighCVSS base score
- 3.9%Exploitation in 30 daysEPSS · top 9.5% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
An issue was discovered in Squid through 4.7 and 5. When receiving a request, Squid checks its cache to see if it can serve up a response. It does this by making a MD5 hash of the absolute URL of the request. If found, it servers the request. The absolute URL can include the decoded UserInfo (username and password) for certain protocols. This decoded info is prepended to the domain. This allows an attacker to provide a username that has special characters to delimit the domain, and treat the rest of the URL as a path or query string. An attacker could first make a request to their domain using an encoded username, then when a request for the target domain comes in that decodes to the exact URL, it will serve the attacker's HTML instead of the real HTML. On Squid servers that also act as reverse proxies, this allows an attacker to gain access to features that only reverse proxies can use, such as ESI.
Timeline
ID reserved
By mitre
- 11 months later
· 11 months later
Published
- 4 years later
· 4 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N |
- EPSS (exploitation in 30 days)
- 3.9% · top 9.5% of all CVEs (13 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Affected products
n/a
- affected n/a
References
References8
- http://www.squid-cache.org/Versions/v4/ (opens in a new tab)x_refsource_MISCx_transferred
- http://www.squid-cache.org/Versions/v4/changesets/ (opens in a new tab)x_refsource_MISCx_transferred
- https://github.com/squid-cache/squid/commits/v4 (opens in a new tab)x_refsource_MISCx_transferred
- https://gitlab.com/jeriko.one/security/-/blob/master/squid/CVEs/CVE-2019-12520.txt (opens in a new tab)x_refsource_MISCx_transferred
- DSA-4682 (opens in a new tab)vendor-advisoryx_refsource_DEBIANx_transferred
- [debian-lts-announce] 20200710 [SECURITY] [DLA 2278-1] squid3 security update (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- USN-4446-1 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
- https://security.netapp.com/advisory/ntap-20210205-0006/ (opens in a new tab)x_refsource_CONFIRMx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2019-4115 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2019-12520)Record last updated .