CVE-2021-25964

Exploitation

Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.

SSVC decision

• ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
• 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

0.55% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 43.8% of scored records. A rank, not a probability.

NVD base score

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

NVD CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/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

No Red Hat rating. Red Hat rates the CVEs that affect its products.

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

2021-10-04 14:55Z4 YR AGO

Last updated

2025-04-30 16:24Z1 YR AGO

Reserved

2021-01-22

Assigning CNA

Mend

Record state

PUBLISHED

Severity

Medium (CVSS 5.4)

CNA CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/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

5.1

Document digest

2f2a016e0a0eb287a5513b54beb54221e8ab4085ed19576ce4bdb79eb1532894

• www.whitesourcesoftware.comhttps://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25964x_refsource_MISC
• github.comhttps://github.com/janeczku/calibre-web/commit/32e27712f0f71fdec646add20cd78b4ce75acfcex_refsource_MISC