CVE-2021-43818

Exploitation

Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.

SSVC decision

• ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
• AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
• Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

2.48% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 83.1% of scored records. A rank, not a probability.

NVD base score

7.1 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

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

NVD analysis status

Modified. NVD last modified this record on 2026-06-17.

Red Hat severity

Moderate. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2021-12-13 18:05Z4 YR AGO

Last updated

2025-12-18 15:05Z8 MO AGO

Reserved

2021-11-16

Assigning CNA

GitHub_M

Record state

PUBLISHED

Severity

High (CVSS 8.2)

CNA CVSS vector

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

Weaknesses

• CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')Class
• CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')Base

Data version

5.2

Document digest

511051bf76cfed5c55f3b806bc1ce50f914baf9ee82d64dfaeffaa22261f5671

• github.comhttps://github.com/lxml/lxml/security/advisories/GHSA-55x5-fj6c-h6m8x_refsource_CONFIRM
• github.comhttps://github.com/lxml/lxml/commit/12fa9669007180a7bb87d990c375cf91ca5b664ax_refsource_MISC
• github.comhttps://github.com/lxml/lxml/commit/a3eacbc0dcf1de1c822ec29fb7d090a4b1712a9c#diff-59130575b4fb2932c957db2922977d7d89afb0b2085357db1a14615a2fcad776x_refsource_MISC
• github.comhttps://github.com/lxml/lxml/commit/f2330237440df7e8f39c3ad1b1aa8852be3b27c0x_refsource_MISC
• lists.fedoraproject.orgFEDORA-2021-6e8fb79f90https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZQ4SPKJX3RRJK4UWA6FXCRHD2TVRQI44/vendor-advisoryx_refsource_FEDORA
• lists.fedoraproject.orgFEDORA-2021-9f9e7c5c4fhttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WZGNET2A4WGLSUXLBFYKNC5PXHQMI3I7/vendor-advisoryx_refsource_FEDORA
• lists.debian.org[debian-lts-announce] 20211230 [SECURITY] [DLA 2871-1] lxml security updatehttps://lists.debian.org/debian-lts-announce/2021/12/msg00037.htmlmailing-listx_refsource_MLIST
• www.debian.orgDSA-5043https://www.debian.org/security/2022/dsa-5043vendor-advisoryx_refsource_DEBIAN
• lists.fedoraproject.orgFEDORA-2022-96c79bf003https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TUIS2KE3HZ2AAQKXFLTJFZPP2IFHJTC7/vendor-advisoryx_refsource_FEDORA
• lists.fedoraproject.orgFEDORA-2022-7129fbaeedhttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/V2XMOM5PFT6U5AAXY6EFNT5JZCKKHK2V/vendor-advisoryx_refsource_FEDORA
• www.oracle.comhttps://www.oracle.com/security-alerts/cpuapr2022.htmlx_refsource_MISC
• security.netapp.comhttps://security.netapp.com/advisory/ntap-20220107-0005/x_refsource_CONFIRM
• www.oracle.comhttps://www.oracle.com/security-alerts/cpujul2022.htmlx_refsource_MISC
• security.gentoo.orgGLSA-202208-06https://security.gentoo.org/glsa/202208-06vendor-advisoryx_refsource_GENTOO