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CVE-2020-27783

23
FAUCET Score

CVE-2020-27783 describes a Cross-Site Scripting (XSS) vulnerability in the python-lxml clean module, impacting products like Debian, Fedora, and Oracle. The flaw stems from the module's parser failing to accurately mimic browser behavior, allowing a remote attacker to inject and execute arbitrary HTML/JS code. Rated as Medium severity (CVSS 6.1), exploitation requires user interaction (UI:R) but has low attack complexity (AC:L), potentially leading to limited confidentiality and integrity impacts. Currently, there is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
>= 1.2, < 4.6.2CPE matchmatch criteria
cpe:2.3:a:lxml:lxml:*:*:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:a:redhat:software_collections:-:*:*:*:*:*:*:*
8.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
9.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.1MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
2.7
CvssVersion
3.1

Exploit Intelligence

EPSS Score
3.93%
Probability of exploitation in next 30 days
EPSS Percentile
89.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0393 is in the 95th percentile among its peer group of 26,221 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (27)

microsoftpatch availablevia msrc
Product: CBL Mariner 2.0 x64Fixed in: 4.8.0-1
microsoftpatch availablevia msrc
Product: 16956-16820Fixed in: 4.6.3-1
microsoftpatch availablevia msrc
Product: 16957-16823Fixed in: 4.8.0-1
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 x64Fixed in: 4.6.3-1
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 ARMFixed in: 4.6.3-1
microsoftpatch availablevia msrc
Product: CBL Mariner 2.0 ARMFixed in: 4.8.0-1
oraclepatch availablevia nvd_reference
View patch
pippatch availablevia ghsa
Product: lxmlFixed in: 4.6.2
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7Fixed in: rh-python38-python-lxml-0:4.4.1-7.el7
View patch
redhatpatch availablevia nvd_reference
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7Fixed in: rh-python38-python-urllib3-0:1.25.7-7.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUSFixed in: rh-python38-babel-0:2.7.0-12.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUSFixed in: rh-python38-python-0:3.8.11-2.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUSFixed in: rh-python38-python-cryptography-0:2.8-5.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUSFixed in: rh-python38-python-jinja2-0:2.10.3-6.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUSFixed in: rh-python38-python-lxml-0:4.4.1-7.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUSFixed in: rh-python38-python-pip-0:19.3.1-2.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUSFixed in: rh-python38-python-urllib3-0:1.25.7-7.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7Fixed in: rh-python38-python-pip-0:19.3.1-2.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: python27:2.7-8040020210122160212.cdb2db54
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: python38:3.8-8040020210128125034.b1b639b6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: python-lxml-0:4.2.3-2.el8
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7Fixed in: rh-python38-babel-0:2.7.0-12.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7Fixed in: rh-python38-python-0:3.8.11-2.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7Fixed in: rh-python38-python-cryptography-0:2.8-5.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7Fixed in: rh-python38-python-jinja2-0:2.10.3-6.el7
View patch
redhatend of lifevia redhat_api
Product: Red Hat OpenStack Platform 13 (Queens)Fixed in: python-lxml

Vendor Advisories (4)

microsoft2021-Jul/CVE-2020-27783

CVE-2020-27783

Jul 13, 2021
pipGHSA-pgww-xf46-h92rmedium

lxml vulnerable to Cross-site Scripting

Jan 7, 2021
microsoft2020-Dec/CVE-2020-27783Moderate

A XSS vulnerability was discovered in python-lxml's clean module. The module's parser didn't properly imitate browsers which caused different behaviors between the sanitizer and the user's page. A remote attacker could exploit this flaw to run arbitrary HTML/JS code.

Dec 8, 2020
redhatCVE-2020-27783Moderate

python-lxml: mXSS due to the use of improper parser

Oct 18, 2020

References

advisory.checkmarx.net / advisory/CX-2020-4286
ExploitThird Party Advisory
bugzilla.redhat.com / show_bug.cgi
ExploitIssue TrackingPatchThird Party Advisory
lists.debian.org / debian-lts-announce/2020/12/msg00028.html
Mailing ListThird Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/JKG67GPGTV23KADT4D4GK4RMHSO4CIQL
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/TMHVKRUT22LVWNL3TB7HPSDHJT74Q3JK
security.netapp.com / advisory/ntap-20210521-0003
Third Party Advisory
debian.org / security/2020/dsa-4810
Third Party Advisory
oracle.com / /security-alerts/cpujul2021.html
PatchThird Party Advisory