CVE-2026-34478

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.
• AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
• 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

0.97% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 61.7% of scored records. A rank, not a probability.

NVD base score

6.9 (CVSS v4.0), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

NVD analysis status

Analyzed. NVD last modified this record on 2026-10-26.

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

2026-04-10 15:40Z6 MO AGO

Last updated

2026-04-10 17:50Z6 MO AGO

Reserved

2026-03-28

Assigning CNA

apache

Record state

PUBLISHED

Severity

Medium (CVSS 6.9)

CNA CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N

Weaknesses

• CWE-117Improper Output Neutralization for LogsBase
• CWE-684Incorrect Provision of Specified FunctionalityClass
• CWE-93Improper Neutralization of CRLF Sequences ('CRLF Injection')Base

Data version

5.2

Document digest

1e69da28af361a88aa98254ebd5d95753f07db1c3abb9be59d968f552728f85f

• github.comhttps://github.com/apache/logging-log4j2/pull/4074patch
• logging.apache.orghttps://logging.apache.org/security.html#CVE-2026-34478vendor-advisory
• logging.apache.orghttps://logging.apache.org/cyclonedx/vdr.xmlvendor-advisory
• logging.apache.orghttps://logging.apache.org/log4j/2.x/manual/layouts.html#RFC5424Layoutrelated
• lists.apache.orghttps://lists.apache.org/thread/3k1clr2l6vkdnl4cbhjrnt1nyjvb5gwtvendor-advisory
• www.openwall.comhttp://www.openwall.com/lists/oss-security/2026/04/10/7