Apache Log4j Core up to 2.25.3/3.0.0-beta3 log4j2.sslVerifyHostName certificate host validation

CVSS Meta Temp Score
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CTI Interest Score
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3.6$0-$5k0.00

Summaryinfo

A vulnerability labeled as critical has been found in Apache Log4j Core up to 2.25.3/3.0.0-beta3. This affects the function log4j2.sslVerifyHostName. Executing a manipulation can lead to certificate host validation. This vulnerability is tracked as CVE-2026-34477. The attack can be launched remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as problematic was found in Apache Log4j Core up to 2.25.3/3.0.0-beta3. This vulnerability affects the function log4j2.sslVerifyHostName. The manipulation with an unknown input leads to a certificate host validation vulnerability. The CWE definition for the vulnerability is CWE-297. The product communicates with a host that provides a certificate, but the product does not properly ensure that the certificate is actually associated with that host. As an impact it is known to affect integrity. CVE summarizes:

The fix for CVE-2025-68161 https://logging.apache.org/security.html#CVE-2025-68161 was incomplete: it addressed hostname verification only when enabled via the log4j2.sslVerifyHostName https://logging.apache.org/log4j/2.x/manual/systemproperties.html#log4j2.sslVerifyHostName system property, but not when configured through the verifyHostName https://logging.apache.org/log4j/2.x/manual/appenders/network.html#SslConfiguration-attr-verifyHostName attribute of the element. Although the verifyHostName configuration attribute was introduced in Log4j Core 2.12.0, it was silently ignored in all versions through 2.25.3, leaving TLS connections vulnerable to interception regardless of the configured value. A network-based attacker may be able to perform a man-in-the-middle attack when all of the following conditions are met: * An SMTP, Socket, or Syslog appender is in use. * TLS is configured via a nested element. * The attacker can present a certificate issued by a CA trusted by the appender's configured trust store, or by the default Java trust store if none is configured. This issue does not affect users of the HTTP appender, which uses a separate verifyHostname https://logging.apache.org/log4j/2.x/manual/appenders/network.html#HttpAppender-attr-verifyHostName attribute that was not subject to this bug and verifies host names by default. Users are advised to upgrade to Apache Log4j Core 2.25.4, which corrects this issue.

The weakness was disclosed by Samuli Leinonen. The advisory is available at github.com. This vulnerability was named CVE-2026-34477 since 03/28/2026. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 06/24/2026). This vulnerability is assigned to T1587.003 by the MITRE ATT&CK project.

The vulnerability scanner Nessus provides a plugin with the ID 315047 (SUSE SLED15 / SLES15 Security Update : log4j (SUSE-SU-2026:1843-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2.25.4 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (315047) and CERT Bund (WID-SEC-2026-1067). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

  • Google Cloud Platform
  • Red Hat Enterprise Linux
  • SUSE Linux
  • IBM SPSS
  • SUSE openSUSE
  • IBM Tivoli Network Manager
  • IBM DB2
  • Microsoft Azure Linux
  • Apache log4j
  • IBM App Connect Enterprise
  • IBM Tivoli Netcool/OMNIbus
  • Splunk Splunk Enterprise
  • IBM License Metric Tool

Productinfo

Vendor

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Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 3.7
VulDB Meta Temp Score: 3.6

VulDB Base Score: 3.7
VulDB Temp Score: 3.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Certificate host validation
CWE: CWE-297 / CWE-295 / CWE-287
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 315047
Nessus Name: SUSE SLED15 / SLES15 Security Update : log4j (SUSE-SU-2026:1843-1)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Log4j Core 2.25.4
Patch: github.com

Timelineinfo

03/28/2026 CVE reserved
04/10/2026 +12 days Advisory disclosed
04/10/2026 +0 days VulDB entry created
06/24/2026 +75 days VulDB entry last update

Sourcesinfo

Vendor: apache.org

Advisory: github.com
Researcher: Samuli Leinonen
Status: Confirmed

CVE: CVE-2026-34477 (🔒)
GCVE (CVE): GCVE-0-2026-34477
GCVE (VulDB): GCVE-100-356842
CERT Bund: WID-SEC-2026-1067 - Apache log4j: Mehrere Schwachstellen ermöglichen Manipulation von Dateien

Entryinfo

Created: 04/10/2026 20:07
Updated: 06/24/2026 21:55
Changes: 04/10/2026 20:07 (69), 04/13/2026 17:50 (7), 05/17/2026 00:45 (2), 06/11/2026 13:59 (1), 06/23/2026 15:51 (1), 06/24/2026 21:55 (1)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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