CVE-2018-20852

MEDIUMNVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

Score 5.3 from GitHub Security Advisory published 2022-05-24. NVD baseline CVSS 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this week
5.3
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 4%CVSS: 5.3Exploit: NoneExposed: 0

A fix is available — apply it.

http.cookiejar.DefaultPolicy.domain_return_ok in Lib/http/cookiejar.py in Python before 3.7.3 does not correctly validate the domain: it can be tricked into sending existing cookies to the wrong server. An attacker may abuse this flaw by using a server with a hostname that has another valid hostname as a suffix (e.g., pythonicexample.com to steal cookies for example.com). When a program uses http.cookiejar.DefaultPolicy and tries to do an HTTP connection to an attacker-controlled server, existing cookies can be leaked to the attacker. This affects 2.x through 2.7.16, 3.x before 3.4.10, 3.5.x before 3.5.7, 3.6.x before 3.6.9, and 3.7.x before 3.7.3.

CVSS v3
5.3
EG Score
5.3(medium)
EG Risk
—
EPSS
89.5%
KEV
Not listed

Published

July 13, 2019

Last Modified

November 21, 2024

References (36)

Vendor Advisories for CVE-2018-20852(4)

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

Patch Availability(11)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntupython3.5-venv (3.5.2-2ubuntu0~16.04.8) @ xenial2026-05-27ubuntu
ubuntupython3.4-venv (3.4.3-1ubuntu1~14.04.7+esm2) @ trusty2026-05-27ubuntu
ubuntupython3.9-venv (3.9.5-3ubuntu0~20.04.1+esm2) @ focal2026-05-27ubuntu
redhatpython3-0:3.6.8-23.el82020-04-28redhat
redhatpython27:2.7-8020020200117110429.90f98d4f2020-04-28redhat
redhatansible-tower-35/ansible-tower:3.5.6-12020-04-22redhat
redhatansible-tower-36/ansible-tower:3.6.4-12020-04-22redhat
redhatpython3-0:3.6.8-13.el72020-03-31redhat
redhatpython-0:2.7.5-88.el72020-03-31redhat
redhatpython27-python-0:2.7.17-2.el72019-11-25redhat
redhatrh-python36-python-0:3.6.9-2.el72019-11-06redhat

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

(7)

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 11× in last 7d / 46× 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 22:15 UTCEG score recompute
  2. 2026-07-22 14:05 UTCEPSS rescore
  3. 2026-07-21 15:22 UTCEPSS rescore
  4. 2026-07-20 17:04 UTCEPSS rescore
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  6. 2026-07-20 13:02 UTCOSV refresh
  7. 2026-07-19 14:28 UTCEPSS rescore
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  1. 2026-07-06 02:20 UTCEPSS rescore
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  3. 2026-07-04 06:28 UTCEPSS rescore
  4. 2026-07-04 06:28 UTCEPSS rescore
  5. 2026-07-03 07:56 UTCOSV refresh
  6. 2026-07-02 16:54 UTCEPSS rescore
  7. 2026-07-01 15:03 UTCEPSS rescore
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  9. 2026-06-30 23:20 UTCEPSS rescore
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  15. 2026-06-25 13:47 UTCEPSS rescore
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  17. 2026-06-24 14:02 UTCEPSS rescore
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  35. 2026-06-15 17:45 UTCEPSS rescore
  36. 2026-06-14 23:15 UTCEPSS rescore
  37. 2026-06-14 23:14 UTCEPSS rescore
  38. 2026-06-14 22:43 UTCOSV refresh
  39. 2026-06-13 22:58 UTCEPSS rescore
  40. 2026-06-12 23:09 UTCEPSS rescore
  41. 2026-06-12 23:09 UTCEPSS rescore
  42. 2026-06-11 13:57 UTCEPSS rescore
  43. 2026-06-10 22:16 UTCEPSS rescore
  44. 2026-06-10 13:19 UTCEPSS rescore
  45. 2026-06-08 14:14 UTCEPSS rescore
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  47. 2026-06-07 15:22 UTCEPSS rescore
  48. 2026-06-07 15:22 UTCEPSS rescore
  49. 2026-06-06 13:45 UTCEPSS rescore
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  60. 2026-05-31 22:29 UTCEPSS rescore
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  63. 2026-05-29 13:41 UTCEPSS rescore
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  65. 2026-05-28 13:42 UTCEPSS rescore
  66. 2026-05-27 17:24 UTCEG score recompute
  67. 2026-05-27 17:24 UTCVendor advisory
  68. 2026-05-27 17:24 UTCGHSA enrichment
  69. 2026-05-27 13:38 UTCEPSS rescore
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  71. 2026-05-26 13:42 UTCEPSS rescore
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  73. 2026-05-26 07:17 UTCEPSS rescore
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Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2018-20852?
CVE-2018-20852 is a medium vulnerability published on July 13, 2019. http.cookiejar.DefaultPolicy.domainreturnok in Lib/http/cookiejar.py in Python before 3.7.3 does not correctly validate the domain: it can be tricked into sending existing cookies to the wrong server. An attacker may abuse this flaw by using a server with a hostname that has another valid hostname…
When was CVE-2018-20852 disclosed?
CVE-2018-20852 was first published in the National Vulnerability Database on July 13, 2019, 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-2018-20852 actively exploited?
CVE-2018-20852 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 89.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2018-20852?
CVE-2018-20852 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2018-20852?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2018-20852, 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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