Cross-site scripting in python-lxml
Priority LOW 34CWE-79Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Cross-site scripting
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- Partial Red Hat: 4 fixed, 5 without a fix
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-79.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.03982 90th percentileScored 2026-11-07
Public exploit Yes 2 exploit referencesTagged by NVD
Fix Partial lxml (PyPI): 4.6.2Red Hat: 4 advisoriesRed Hat: 4 fixed, 5 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | python-lxml | lxml-4.6.2 | — | No fix listed | CNA |
| — | lxml (PyPI) | before 4.6.2 | 4.6.2 | Patch available | GHSA-pgww-xf46-h92r |
- python-lxml Vendor— Affected lxml-4.6.2 Fixed in — No fix listed CNA
- lxml (PyPI) Vendor— Affected before 4.6.2 Fixed in 4.6.2 Patch available GHSA-pgww-xf46-h92r
CPE configurations NVD · 10
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:lxml:lxml:*:*:*:*:*:*:*:* | 1.2 to before 4.6.2 | Vulnerable | lxml |
| cpe:2.3:a:redhat:software_collections:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | Red Hat |
| cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:* | 8.0 | Vulnerable | Red Hat |
| cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* | 9.0 | Vulnerable | Debian |
| cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* | 10.0 | Vulnerable | Debian |
| cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:* | 32 | Vulnerable | Fedoraproject |
| cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* | 33 | Vulnerable | Fedoraproject |
| cpe:2.3:a:netapp:snapcenter:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:a:oracle:communications_offline_mediation_controller:12.0.0.3.0:*:*:*:*:*:*:* | 12.0.0.3.0 | Vulnerable | Oracle |
| cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:* | 8.8 | Vulnerable | Oracle |
- cpe:2.3:a:lxml:lxml:*:*:*:*:*:*:*:* Versions 1.2 to before 4.6.2 Vulnerable ·lxml
- cpe:2.3:a:redhat:software_collections:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Red Hat
- cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:* Versions 8.0 Vulnerable ·Red Hat
- cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Debian
- cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* Versions 10.0 Vulnerable ·Debian
- cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:* Versions 32 Vulnerable ·Fedoraproject
- cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* Versions 33 Vulnerable ·Fedoraproject
- cpe:2.3:a:netapp:snapcenter:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:a:oracle:communications_offline_mediation_controller:12.0.0.3.0:*:*:*:*:*:*:* Versions 12.0.0.3.0 Vulnerable ·Oracle
- cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:* Versions 8.8 Vulnerable ·Oracle
Remediation
- Fix · GHSA-pgww-xf46-h92r lxml (PyPI) Fixed in 4.6.2 Advisory →
Red Hat 4 advisories
- RHSA-2021:3254 Released 2021-08-24 · Red Hat rating Moderaterh-python38 security, bug fix, and enhancement update
- Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7) rh-python38-babel-2.7.0-12.el7, rh-python38-python-3.8.11-2.el7, rh-python38-python-babel-2.7.0-12.el7 +14
- Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.7) rh-python38-babel-2.7.0-12.el7, rh-python38-python-3.8.11-2.el7, rh-python38-python-babel-2.7.0-12.el7 +14
- Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7) rh-python38-babel-2.7.0-12.el7, rh-python38-python-3.8.11-2.el7, rh-python38-python-babel-2.7.0-12.el7 +14
- RHSA-2021:1898 Released 2021-05-18 · Red Hat rating Moderatepython-lxml security update
- Red Hat Enterprise Linux AppStream (v. 8) python-lxml-4.2.3-2.el8, python3-lxml-4.2.3-2.el8
- RHSA-2021:1879 Released 2021-05-18 · Red Hat rating Moderatepython38:3.8 security update
- Red Hat Enterprise Linux AppStream (v. 8) Cython-0.29.14-4.module+el8.4.0+8888+89bc7e79.src::python38:3.8, PyYAML-5.3.1-1.module+el8.4.0+8888+89bc7e79.src::python38:3.8, babel-2.7.0-10.module+el8.4.0+8888+89bc7e79.src::python38:3.8 +47
Show 1 more Red Hat advisories
- RHSA-2021:1761 Released 2021-05-18 · Red Hat rating Moderatepython27:2.7 security and bug fix update
- Red Hat Enterprise Linux AppStream (v. 8) Cython-0.28.1-7.module+el8.1.0+3111+de3f2d8e.src::python27:2.7, PyYAML-3.12-16.module+el8.1.0+3111+de3f2d8e.src::python27:2.7, babel-2.5.1-9.module+el8.1.0+3111+de3f2d8e.noarch::python27:2.7 +47
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 5 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | Affected | No fix planned: Out of support scope |
| Red Hat OpenStack Platform 10 (Newton) | Affected | No fix planned: Out of support scope |
| Red Hat OpenStack Platform 13 (Queens) | Affected | No fix planned: Will not fix |
| Red Hat Enterprise Linux AppStream (v. 8) | Fixed | RHSA-2021:1761, RHSA-2021:1879, RHSA-2021:1898 |
| Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7) | Fixed | RHSA-2021:3254 |
| Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.7) | Fixed | RHSA-2021:3254 |
| Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7) | Fixed | RHSA-2021:3254 |
Not affected: 1 product
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2020-27783
- 2026-10-03 Alias added: GHSA-pgww-xf46-h92r
References
Exploit 2
Advisory 7
Other 9
- https://github.com/lxml/lxml/commit/a105ab8dc262ec6735977c25c13f0bdfcdec72a7
- https://security.netapp.com/advisory/ntap-20210521-0003
- https://pypi.org/project/lxml
- https://lists.fedoraproject.org/archives/list/[email protected]/message/TMHVKRUT22LVWNL3TB7HPSDHJT74Q3JK
- https://lists.fedoraproject.org/archives/list/[email protected]/message/JKG67GPGTV23KADT4D4GK4RMHSO4CIQL
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TMHVKRUT22LVWNL3TB7HPSDHJT74Q3JK
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JKG67GPGTV23KADT4D4GK4RMHSO4CIQL
- https://github.com/pypa/advisory-database/tree/main/vulns/lxml/PYSEC-2020-62.yaml
- https://github.com/lxml/lxml
Sources
- CVE-2020-27783 · CVE Program
- CVE-2020-27783 · NVD
- FIRST EPSS
- GHSA-pgww-xf46-h92r · GitHub Advisory Database · CC BY 4.0
- CVE-2020-27783 · Red Hat security data · CC BY 4.0
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