CVE-2021-28957

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

4.04% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 89.9% of scored records. A rank, not a probability.

NVD base score

6.1 (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:N

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

2021-03-21 04:39Z5 YR AGO

Last updated

2025-12-17 21:31Z8 MO AGO

Reserved

2021-03-21

Assigning CNA

mitre

Record state

PUBLISHED

Severity

Medium (CVSS 6.1)

CNA CVSS vector

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

Weaknesses

• CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')Base

Data version

5.2

Document digest

7499d28aa430b7341061e730624aa6b160b7fb39eabe5a7ee4999b259a508f72

• bugs.launchpad.nethttps://bugs.launchpad.net/lxml/+bug/1888153x_refsource_MISC
• github.comhttps://github.com/lxml/lxml/pull/316/commits/10ec1b4e9f93713513a3264ed6158af22492f270x_refsource_MISC
• lists.debian.org[debian-lts-announce] 20210324 [SECURITY] [DLA 2606-1] lxml security updatehttps://lists.debian.org/debian-lts-announce/2021/03/msg00031.htmlmailing-listx_refsource_MLIST
• www.debian.orgDSA-4880https://www.debian.org/security/2021/dsa-4880vendor-advisoryx_refsource_DEBIAN
• lists.fedoraproject.orgFEDORA-2021-28723f9670https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3C2R44VDUY7FJVMAVRZ2WY7XYL4SVN45/vendor-advisoryx_refsource_FEDORA
• lists.fedoraproject.orgFEDORA-2021-4cdb0f68c7https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XXN3QPWCTQVOGW4BMWV3AUUZZ4NRZNSQ/vendor-advisoryx_refsource_FEDORA
• www.oracle.comhttps://www.oracle.com/security-alerts/cpuoct2021.htmlx_refsource_MISC
• github.comhttps://github.com/lxml/lxml/commit/a5f9cb52079dc57477c460dbe6ba0f775e14a999x_refsource_MISC
• security.netapp.comhttps://security.netapp.com/advisory/ntap-20210521-0004/x_refsource_CONFIRM
• security.gentoo.orgGLSA-202208-06https://security.gentoo.org/glsa/202208-06vendor-advisoryx_refsource_GENTOO