CVE-2018-20852
http.cookiejar.DefaultPolicy.domain_return_ok in Lib/http/cookiejar.py in Python before 3.7.3 does not correctly validate the domain: it…
- 4.3MediumCVSS base score
- 3.7%Exploitation in 30 daysEPSS · top 10% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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.
Timeline
ID reserved
By mitre
Published
- 7 years later
· 7 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 |
|---|---|---|---|
| CISA-ADPADP (enrichment) | 3.1 | Medium4.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N |
| NVDNVD · Modified | 3.1 | Medium4.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N |
- EPSS (exploitation in 30 days)
- 3.7% · top 10% of all CVEs (10 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 4.3.
Affected products
n/a
- affected n/a
References
18
- https://bugs.python.org/issue35121 (opens in a new tab)x_refsource_MISCx_transferred
- https://python-security.readthedocs.io/vuln/cookie-domain-check.html (opens in a new tab)x_refsource_MISCx_transferred
- [debian-lts-announce] 20190817 [SECURITY] [DLA 1889-1] python3.4 security update (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- openSUSE-SU-2019:1988 (opens in a new tab)vendor-advisoryx_refsource_SUSEx_transferred
- openSUSE-SU-2019:1989 (opens in a new tab)vendor-advisoryx_refsource_SUSEx_transferred
- [debian-lts-announce] 20190831 [SECURITY] [DLA 1906-1] python2.7 security update (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- USN-4127-2 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
- USN-4127-1 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
- RHSA-2019:3725 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- FEDORA-2019-0d3fcae639 (opens in a new tab)vendor-advisoryx_refsource_FEDORAx_transferred
- FEDORA-2019-74ba24605e (opens in a new tab)vendor-advisoryx_refsource_FEDORAx_transferred
- FEDORA-2019-758824a3ff (opens in a new tab)vendor-advisoryx_refsource_FEDORAx_transferred
- RHSA-2019:3948 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- openSUSE-SU-2020:0086 (opens in a new tab)vendor-advisoryx_refsource_SUSEx_transferred
- GLSA-202003-26 (opens in a new tab)vendor-advisoryx_refsource_GENTOOx_transferred
- https://www.oracle.com/security-alerts/cpuapr2020.html (opens in a new tab)x_refsource_MISCx_transferred
- [debian-lts-announce] 20200715 [SECURITY] [DLA 2280-1] python3.5 security update (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- [debian-lts-announce] 20200822 [SECURITY] [DLA 2337-1] python2.7 security update (opens in a new tab)mailing-listx_refsource_MLISTx_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-2018-13392 (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-2018-20852)Record last updated .