CVE-2019-12520

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 3.9%, top 11% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Trending — 3 sources updated this week
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 4%CVSS: 7.5Exploit: NoneExposed: 0

A fix is available — apply it.

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.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
—
EPSS
89.3%
KEV
Not listed

Published

April 15, 2020

Last Modified

November 21, 2024

References (16)

Vendor Advisories for CVE-2019-12520(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntusquidclient (3.5.12-1ubuntu7.12) @ xenial2026-05-27ubuntu
redhatsquid:4-8030020200828070549.30b713e62020-11-04redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 13× in last 7d / 45× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-22 22:19 UTCEG score recompute
  2. 2026-07-22 14:05 UTCEPSS rescore
  3. 2026-07-21 15:22 UTCEPSS rescore
  4. 2026-07-21 15:22 UTCEPSS rescore
  5. 2026-07-20 17:04 UTCEPSS rescore
  6. 2026-07-19 14:28 UTCEPSS rescore
  7. 2026-07-19 14:28 UTCEPSS rescore
  8. 2026-07-19 14:24 UTCOSV refresh
  9. 2026-07-19 02:26 UTCEPSS rescore
  10. 2026-07-19 02:26 UTCEPSS rescore
  11. 2026-07-18 10:01 UTCEPSS rescore
  12. 2026-07-16 16:59 UTCEPSS rescore
  13. 2026-07-16 16:59 UTCEPSS rescore
  14. 2026-07-15 16:55 UTCEPSS rescore
  15. 2026-07-13 22:27 UTCEPSS rescore
  16. 2026-07-13 06:10 UTCEPSS rescore
  17. 2026-07-13 06:10 UTCEPSS rescore
  18. 2026-07-12 05:43 UTCEPSS rescore
  19. 2026-07-11 08:24 UTCEPSS rescore
  20. 2026-07-09 19:06 UTCEPSS rescore
  21. 2026-07-08 15:11 UTCEPSS rescore
  22. 2026-07-07 13:42 UTCEPSS rescore
  23. 2026-07-06 16:25 UTCEPSS rescore
  24. 2026-07-06 02:20 UTCEPSS rescore
  25. 2026-07-05 02:27 UTCEPSS rescore
Show 68 more
  1. 2026-07-04 06:28 UTCEPSS rescore
  2. 2026-07-04 06:28 UTCEPSS rescore
  3. 2026-07-02 16:56 UTCEPSS rescore
  4. 2026-07-02 00:25 UTCOSV refresh
  5. 2026-07-01 15:03 UTCEPSS rescore
  6. 2026-07-01 15:03 UTCEPSS rescore
  7. 2026-06-30 23:20 UTCEPSS rescore
  8. 2026-06-30 23:20 UTCEPSS rescore
  9. 2026-06-29 14:03 UTCEPSS rescore
  10. 2026-06-28 14:04 UTCEPSS rescore
  11. 2026-06-28 04:54 UTCEPSS rescore
  12. 2026-06-28 04:53 UTCEPSS rescore
  13. 2026-06-27 03:06 UTCEPSS rescore
  14. 2026-06-27 03:06 UTCEPSS rescore
  15. 2026-06-25 13:47 UTCEPSS rescore
  16. 2026-06-25 13:47 UTCEPSS rescore
  17. 2026-06-24 14:03 UTCEPSS rescore
  18. 2026-06-24 14:02 UTCEPSS rescore
  19. 2026-06-23 21:30 UTCEPSS rescore
  20. 2026-06-23 21:30 UTCEPSS rescore
  21. 2026-06-21 14:54 UTCEPSS rescore
  22. 2026-06-21 14:54 UTCEPSS rescore
  23. 2026-06-21 01:57 UTCEPSS rescore
  24. 2026-06-21 01:57 UTCEPSS rescore
  25. 2026-06-19 19:23 UTCEPSS rescore
  26. 2026-06-19 19:23 UTCEPSS rescore
  27. 2026-06-18 17:50 UTCEPSS rescore
  28. 2026-06-17 17:50 UTCEPSS rescore
  29. 2026-06-16 17:50 UTCEPSS rescore
  30. 2026-06-15 17:45 UTCEPSS rescore
  31. 2026-06-14 23:15 UTCEPSS rescore
  32. 2026-06-14 23:15 UTCEPSS rescore
  33. 2026-06-14 04:43 UTCOSV refresh
  34. 2026-06-13 22:58 UTCEPSS rescore
  35. 2026-06-12 23:09 UTCEPSS rescore
  36. 2026-06-11 13:58 UTCEPSS rescore
  37. 2026-06-11 13:58 UTCEPSS rescore
  38. 2026-06-10 22:16 UTCEPSS rescore
  39. 2026-06-10 13:19 UTCEPSS rescore
  40. 2026-06-08 14:15 UTCEPSS rescore
  41. 2026-06-08 14:14 UTCEPSS rescore
  42. 2026-06-07 15:23 UTCEPSS rescore
  43. 2026-06-07 15:22 UTCEPSS rescore
  44. 2026-06-06 13:45 UTCEPSS rescore
  45. 2026-06-06 13:45 UTCEPSS rescore
  46. 2026-06-05 22:45 UTCEPSS rescore
  47. 2026-06-05 22:45 UTCEPSS rescore
  48. 2026-06-05 06:08 UTCEPSS rescore
  49. 2026-06-05 06:08 UTCEPSS rescore
  50. 2026-06-04 13:10 UTCEPSS rescore
  51. 2026-06-04 13:10 UTCEPSS rescore
  52. 2026-06-02 20:11 UTCEPSS rescore
  53. 2026-06-01 13:50 UTCEPSS rescore
  54. 2026-06-01 13:50 UTCEPSS rescore
  55. 2026-05-31 22:29 UTCEPSS rescore
  56. 2026-05-31 22:29 UTCEPSS rescore
  57. 2026-05-31 00:14 UTCEPSS rescore
  58. 2026-05-31 00:14 UTCEPSS rescore
  59. 2026-05-29 13:42 UTCEPSS rescore
  60. 2026-05-28 13:43 UTCEPSS rescore
  61. 2026-05-27 13:38 UTCEPSS rescore
  62. 2026-05-27 04:49 UTCEG score recompute
  63. 2026-05-27 04:49 UTCVendor advisory
  64. 2026-05-27 04:49 UTCGHSA enrichment
  65. 2026-05-26 13:42 UTCEPSS rescore
  66. 2026-05-26 13:42 UTCEPSS rescore
  67. 2026-05-26 07:17 UTCEPSS rescore
  68. 2026-05-26 07:17 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2019-12520?
CVE-2019-12520 is a high vulnerability published on April 15, 2020. 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…
When was CVE-2019-12520 disclosed?
CVE-2019-12520 was first published in the National Vulnerability Database on April 15, 2020, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2019-12520 actively exploited?
CVE-2019-12520 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 89.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2019-12520?
CVE-2019-12520 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2019-12520?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2019-12520, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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