CVE-2026-34481

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.1%, top 82% 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
Trending — 3 sources updated this week
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 7.5Exploit: NoneExposed: 0

A fix is available — apply it.

Apache Log4j's JsonTemplateLayout https://logging.apache.org/log4j/2.x/manual/json-template-layout.html , in versions up to and including 2.25.3, produces invalid JSON output when log events contain non-finite floating-point values (NaN, Infinity, or -Infinity), which are prohibited by RFC 8259. This may cause downstream log processing systems to reject or fail to index affected records.

An attacker can exploit this issue only if both of the following conditions are met:

* The application uses JsonTemplateLayout. * The application logs a MapMessage, or logs an object directly (e.g., via Logger.info(Object), which wraps it in an ObjectMessage), where the message contains an attacker-controlled floating-point value.

Users are advised to upgrade to Apache Log4j JSON Template Layout 2.25.4, which corrects this issue.

Note: The fix released in version 2.25.4 did not cover all affected code paths. CVE-2026-49844 was assigned to the remaining issue, which concerns the MapMessage.asJson() serialization in Apache Log4j API and is fixed in versions 2.25.5 and 2.26.1.

CVSS v3
7.5
EG Score
7.5(medium)
EPSS
42.5%
KEV
Not listed

Published

April 10, 2026

Last Modified

July 11, 2026

Advisory Details (6)

Auto-updated Jun 15, 2026
Patch available. Sources: github_pr.
generic

oss-security - CVE-2026-34481: Apache Log4j JSON Template Layout: Improper serialization of non-finite floating-point values in JsonTemplateLayout

http://www.openwall.com/lists/oss-security/2026/04/10/10
generic

Security :: Apache Logging Services

https://logging.apache.org/security.html#CVE-2026-34481
generic

JSON Template Layout :: Apache Log4j

https://logging.apache.org/log4j/2.x/manual/json-template-layout.html
generic
https://logging.apache.org/cyclonedx/vdr.xml
generic
https://lists.apache.org/thread/n34zdv00gbkdbzt2rx9rf5mqz6lhopcv
github_pr Patch Available

JsonWriter: Write non-finite floating-point values as strings

Patch available: apache/logging-log4j2 rel/2.25.4 (PR #4080 merged 2026-03-24)

https://github.com/apache/logging-log4j2/pull/4080

Vendor Advisories for CVE-2026-34481(4)

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

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatlog4j-layout-template-json2026-06-02redhat
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-layout-template-json3.0.0-alpha1, 3.0.0-beta1, 3.0.0-beta2, 3.0.0-beta3——

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 44× 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 106 total refreshes for this CVE.

  1. 2026-07-15 16:57 UTCEPSS rescore
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  9. 2026-07-11 06:21 UTCNVD updateCVSS v3 → 7.5 · severity → HIGH
  10. 2026-07-11 05:32 UTCMITRE cvelistV5CVSS v3 → 6.3 · severity → MEDIUM
  11. 2026-07-09 19:10 UTCEPSS rescore
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  22. 2026-06-15 04:23 UTCVendor advisory
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  27. 2026-06-11 20:04 UTCEG score recompute
  28. 2026-06-11 20:04 UTCVendor advisory
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  32. 2026-06-10 13:08 UTCEG score recompute
  33. 2026-06-10 13:08 UTCVendor advisory
  34. 2026-06-10 00:56 UTCEG score recompute
  35. 2026-06-10 00:56 UTCVendor advisory
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  37. 2026-06-09 12:42 UTCVendor advisory
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  40. 2026-06-08 08:25 UTCEG score recompute
  41. 2026-06-08 08:25 UTCVendor advisory
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  43. 2026-06-07 20:14 UTCVendor advisory
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  48. 2026-06-07 08:02 UTCVendor advisory
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  56. 2026-06-02 23:44 UTCVendor advisory
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Frequently asked(5)

What is CVE-2026-34481?
CVE-2026-34481 is a high vulnerability published on April 10, 2026. Apache Log4j's JsonTemplateLayout https://logging.apache.org/log4j/2.x/manual/json-template-layout.html , in versions up to and including 2.25.3, produces invalid JSON output when log events contain non-finite floating-point values (NaN, Infinity, or -Infinity), which are prohibited by RFC 8259.…
When was CVE-2026-34481 disclosed?
CVE-2026-34481 was first published in the National Vulnerability Database on April 10, 2026, with the most recent update on July 11, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-34481 actively exploited?
CVE-2026-34481 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 42.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-34481?
CVE-2026-34481 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-34481?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-34481, 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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