CVE-2026-34477

MEDIUMNVD 5.95.9—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.9 under NVD CVSS v3. EPSS exploit probability: 0.0%, top 91% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
5.9
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.9Exploit: NoneExposed: 0

A fix is available — apply it.

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.

CVSS v3
5.9
EG Score
5.9(medium)
EPSS
31.8%
KEV
Not listed

Published

April 10, 2026

Last Modified

May 6, 2026

Advisory Details (5)

Auto-updated May 6, 2026
No patch confirmed yet.
generic

Security :: Apache Logging Services

https://logging.apache.org/security.html#CVE-2026-34477
generic

Network Appenders :: Apache Log4j

https://logging.apache.org/log4j/2.x/manual/appenders/network.html#SslConfiguration-attr-verifyHostName
generic
https://logging.apache.org/cyclonedx/vdr.xml
generic
https://lists.apache.org/thread/lkx8cl46t2bvkcwfcb2pd43ygc097lq4
generic

Align `SslConfiguration` factory method usage with Log4j 2.12+ API by ppkarwasz · Pull Request #4075 · apache/logging-log4j2 · GitHub

https://github.com/apache/logging-log4j2/pull/4075

Vendor Advisories for CVE-2026-34477(3)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatoffline-knowledge-portal/rhokp-rhel9:17799969992026-05-28redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
Maven(1)
PackageVulnerable rangeFixed inDependents
org.apache.logging.log4j:log4j-core3.0.0-alpha1, 3.0.0-beta1, 3.0.0-beta2, 3.0.0-beta3——

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 9× in last 7d / 42× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 103 total refreshes for this CVE.

  1. 2026-07-15 16:57 UTCEPSS rescore
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  1. 2026-06-27 03:08 UTCEPSS rescore
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  19. 2026-06-15 04:24 UTCEG score recompute
  20. 2026-06-15 04:24 UTCVendor advisory
  21. 2026-06-14 23:18 UTCEPSS rescore
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  25. 2026-06-11 20:07 UTCEG score recompute
  26. 2026-06-11 20:07 UTCVendor advisory
  27. 2026-06-11 14:00 UTCEPSS rescore
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  30. 2026-06-10 12:30 UTCEG score recompute
  31. 2026-06-10 12:30 UTCVendor advisory
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  37. 2026-06-08 07:50 UTCVendor advisory
  38. 2026-06-07 15:25 UTCEPSS rescore
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  41. 2026-06-07 08:03 UTCEG score recompute
  42. 2026-06-07 08:03 UTCVendor advisory
  43. 2026-06-06 13:47 UTCEPSS rescore
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  51. 2026-06-02 23:44 UTCEG score recompute
  52. 2026-06-02 23:44 UTCVendor advisory
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  73. 2026-05-23 00:08 UTCEG score recompute
  74. 2026-05-20 22:38 UTCEPSS rescore
  75. 2026-05-20 22:38 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2026-34477?
CVE-2026-34477 is a medium vulnerability published on April 10, 2026. 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…
When was CVE-2026-34477 disclosed?
CVE-2026-34477 was first published in the National Vulnerability Database on April 10, 2026, with the most recent update on May 6, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-34477 actively exploited?
CVE-2026-34477 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 31.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-34477?
CVE-2026-34477 has a CVSS v3 base score of 5.9 (NVD).
How do I remediate CVE-2026-34477?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-34477, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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