XSS in Lxml
CVE-2021-43818
lxml is a library for processing XML and HTML in the Python language. Prior to version 4.6.5, the HTML Cleaner in lxml.html lets certain crafted script content pass through, as well as script content in SVG files embedded using data URIs. Users that employ the HTML cleaner in a security relevant context should upgrade to lxml 4.6.5 to receive a patch. There are no known workarounds available.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:N.
EPSS exploit prediction
EPSS: 0.027 (85.5th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 85th percentile — 85.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.025 · newest: 0.027 · change: +0.002
Affected products
- Lxml — versions < 4.6.5
- NetApp Hci Storage Node
- NetApp Hci Storage Node Firmware
- NetApp Solidfire
- NetApp Solidfire Enterprise Sds
- Oracle Communications Cloud Native Core Binding Support Function — versions 22.1.3
- Oracle Communications Cloud Native Core Network Exposure Function — versions 22.1.1
- Oracle Communications Cloud Native Core Policy — versions 22.2.0
- Oracle HTTP Server — versions 12.2.1.3.0, 12.2.1.4.0
- Oracle Zfs Storage Appliance Kit — versions 8.8
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/lxml/lxml/security/advisories/GHSA-55x5-fj6c-h6m8 (Third Party Advisory)
- github.com/lxml/lxml/commit/12fa9669007180a7bb87d990c375cf91ca5b664a (Patch, Third Party Advisory)
- github.com/lxml/lxml/commit/a3eacbc0dcf1de1c822ec29fb7d090a4b1712a9c (Patch, Third Party Advisory)
- github.com/lxml/lxml/commit/f2330237440df7e8f39c3ad1b1aa8852be3b27c0 (Patch, Third Party Advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- lists.debian.org/debian-lts-announce/2021/12/msg00037.html (mailing-list, Mailing List, Third Party Advisory)
- www.debian.org/security/2022/dsa-5043 (vendor-advisory, Third Party Advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
Frequently asked questions
- What is CVE-2021-43818?
- CVE-2021-43818 is a high-severity vulnerability in Lxml, classified under Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection). CVSS score: 8.2/10. Published 2021-12-13.
- How severe is CVE-2021-43818?
- High severity. CVSS v3 base score is 8.2 out of 10.
- Is CVE-2021-43818 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.