CVE-2018-20852

NameCVE-2018-20852
Descriptionhttp.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.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDLA-1889-1, DLA-1906-1, DLA-2280-1, DLA-2337-1

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
python2.7sourcejessie2.7.9-2+deb8u4DLA-1906-1
python2.7sourcestretch2.7.13-2+deb9u4DLA-2337-1
python2.7sourcebuster2.7.16-2+deb10u1
python2.7source(unstable)2.7.16-3
python3.4sourcejessie3.4.2-1+deb8u6DLA-1889-1
python3.4source(unstable)(unfixed)
python3.5sourcestretch3.5.3-1+deb9u2DLA-2280-1
python3.5source(unstable)(unfixed)
python3.7source(unstable)3.7.3~rc1-1

Notes

https://bugs.python.org/issue35121
https://python-security.readthedocs.io/vuln/cookie-domain-check.html
https://github.com/python/cpython/commit/979daae300916adb399ab5b51410b6ebd0888f13 (2.7.x branch)
https://github.com/python/cpython/commit/42ad4101d3ba7ca3c371dadf0f8880764c9f15fb (v3.4.10)
https://github.com/python/cpython/commit/4749f1b69000259e23b4cc6f63c542a9bdc62f1b (v3.5.7)
https://github.com/python/cpython/commit/b241af861b37e20ad30533bc0b7e2e5491cc470f (v3.6.9rc1)
https://github.com/python/cpython/commit/e5123d81ffb3be35a1b2767d6ced1a097aaf77be (v3.7.3rc1)

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