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CVE-2026-49844 Apache Log4j

Affected softwareApache Log4j
Severity6.3 Medium CVSS 4.0 2 scores
Fixed in2.25.5, 2.26.1
WeaknessCWE-116
Published10 Jul 2026
Updated25 Oct 2026

Description

Improper encoding of non-finite floating-point values during MapMessage JSON serialization in Apache Log4j API produces output that is not valid JSON. This issue affects Apache Log4j API versions 2.13.1 through 2.25.4 and version 2.26.0. The fix for CVE-2026-34481 did not cover all code paths: when a MapMessage contains a non-finite IEEE 754 value (NaN, Infinity, or -Infinity), MapMessage.asJson() emits the corresponding bare token. RFC 8259 does not permit these tokens, so a conformant parser rejects the resulting document. The defect is reachable only when both of the following conditions hold: * The application uses the message resolver https://logging.apache.org/log4j/2.x/manual/json-template-layout.html#event-template-resolver-message of JsonTemplateLayout or any other layout that relies on MapMessage.asJson() or MapMessage.getFormattedMessage(new String[]{"JSON"}). * The application logs a MapMessage that contains an attacker-controlled floating-point value. An attacker who can supply a non-finite value can cause the affected layout to emit malformed JSON, which may corrupt the enclosing log record or disrupt downstream log ingestion and parsing. Users are advised to upgrade to Apache Log4j API 2.25.5 or 2.26.1, both of which emit RFC 8259-compliant JSON for non-finite values.

Exploitation status

No public exploit

No exploit has been reported in the sources we check. The 1 repository below are public GitHub repositories with fewer than 5 stars.
  • CISA KEV not listed
  • VulnCheck KEV not listed
  • CISA Vulnrichment exploitation: none
  • Indexed PoC 1 indexed, none at 5+ stars
  • EPSS 0.60% chance in 30 days

1 of these are GitHub repositories with fewer than 5 stars. They are listed for reference and don't count toward the exploitation status above.

IndexArtifactStarsFirst seen
GitHub PoC log4j 2025/2026 年 7 条「配置静默失效」CVE 自查:按 CVE×模块 判定 4 个模块,结构化解析 log4j2 配置做 applicability 降噪,并算出该升到哪个版本才一次到位(6 条写 2.25.4,但有一条要 2.25.5,而它 Dependabot 报不出来) CVE-2026-49844 / CVE-2026-34477 2026-08-07

Waratek protection

No exploit published

Within Waratek scope. In the sources we check, nobody has published exploit code for this CVE or reported it being exploited.

A public code fix exists: apache/logging-log4j2 #4163.

  • Protection none
  • Action unverified
  • Review automated Upstream data
  • Record active
Decided by Exploit code for this candidate, published in a reviewed catalogue or a GitHub repository with 5 or more stars, or in use per CISA or VulnCheck; not only a CISA verdict, a forecast, or nothing at all
Finding This CVE is not listed in CISA KEV or VulnCheck KEV, CISA Vulnrichment records no active exploitation, no reviewed exploit catalogue carries an entry for it, and no GitHub PoC repository for it has 5 or more stars. Nobody has published exploit code worth tracing, so it is not a candidate for a rule ahead of the ones where somebody has; an upstream fix path does exist, so the remediation half of the candidacy still holds. This is a statement about what has been published, not about whether the defect is reachable or serious.
Candidate fix https://github.com/apache/logging-log4j2/pull/4163 : a pull request: the change under review

CVSS

6.3 MEDIUM v4.0 CVSS:4.0/AV:N/AC:L/AT:P/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 2 metrics

We show the highest score from the newest CVSS version. Scores from different versions can't be compared, and the first score listed is sometimes a 0.0 placeholder.

VersionScoreBandVectorAssignerType
CVSS 4.0 6.3 MEDIUM CVSS:4.0/AV:N/AC:L/AT:P/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 security@apache.org Secondary published
CVSS 3.1 5.9 MEDIUM CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N NVD Primary

Affected software and releases

Oracle advisories

AdvisoryTypeQuarterProducts Oracle names in its risk matrix
Oracle Critical Patch Update October 2026 ↗ CPU 2026-Q4 Oracle Commerce / Dynamo Application Framework (Apache Log4j) (11.4.0)
Oracle Communications / Platform (Apache Log4j) (15.0.0.0.0, 15.0.1.0.0, 15.1.0.0.0, 15.2.0.0.0)
Oracle Construction and Engineering / Platform (Apache Log4j) (21.12.0-21.12.17, 22.12.0-22.12.15, 23.12.0-23.12.16, 24.12.0-24.12.16, 25.12.0-25.12.9)
Oracle Financial Services Applications / Platform (Apache Log4j) (8.0.7.9, 8.0.8.7, 8.1.2.5, 8.1.2.6)
Oracle Fusion Middleware / Centralized Thirdparty Jars (Apache Log4j) (12.2.1.4.0)
Oracle Fusion Middleware / Third Party (Apache Log4j) (12.2.1.4.0)
Oracle Fusion Middleware / Third Party (Apache Log4j) (14.1.2.0.0)
Oracle Utilities Applications / Security (Apache Log4j) (4.4.0.2.0, 4.4.0.3.0, 4.4.0.4.0, 4.5.0.0.0, 4.5.0.1.1, 4.5.0.1.3, 4.5.0.2.0, 25.4, 25.10, 26.4, 26.10)
Oracle Critical Security Patch Update September 2026 ↗ CSPU 2026-Q3 Oracle Communications / Core (Apache Log4j) (6.1.1-7.0.0)
Oracle Enterprise Manager / OMS (Apache Log4j) (13.5, 24.1)

Oracle components and versions

FamilyComponentVersions, as Oracle lists themRead as
Oracle Commerce Dynamo Application Framework (Apache Log4j) 11.4.0 11.4.0
Oracle Communications Core (Apache Log4j) 6.1.1-7.0.0
Oracle Communications Platform (Apache Log4j) 15.0.0.0.0, 15.0.1.0.0, 15.1.0.0.0, 15.2.0.0.0 15.0.0.0.0 · 15.0.1.0.0 · 15.1.0.0.0 · 15.2.0.0.0
Oracle Construction and Engineering Platform (Apache Log4j) 21.12.0-21.12.17, 22.12.0-22.12.15, 23.12.0-23.12.16, 24.12.0-24.12.16, 25.12.0-25.12.9
Oracle Enterprise Manager OMS (Apache Log4j) 13.5, 24.1 13.5 · 24.1
Oracle Financial Services Applications Platform (Apache Log4j) 8.0.7.9, 8.0.8.7, 8.1.2.5, 8.1.2.6 8.0.7.9 · 8.0.8.7 · 8.1.2.5 · 8.1.2.6
Oracle Fusion Middleware Centralized Thirdparty Jars (Apache Log4j) 12.2.1.4.0 12.2.1.4.0
Oracle Fusion Middleware Third Party (Apache Log4j) 12.2.1.4.0 12.2.1.4.0 · 14.1.2.0.0
Oracle Utilities Applications Security (Apache Log4j) 4.4.0.2.0, 4.4.0.3.0, 4.4.0.4.0, 4.5.0.0.0, 4.5.0.1.1, 4.5.0.1.3, 4.5.0.2.0, 25.4, 25.10, 26.4, 26.10 4.4.0.2.0 · 4.4.0.3.0 · 4.4.0.4.0 · 4.5.0.0.0 · 4.5.0.1.1 · 4.5.0.1.3 · 4.5.0.2.0 · 25.4 · 25.10 · 26.4 · 26.10

Maven packages

Affected and fixed versions, from OSV.dev
PackageIntroducedFixedLast affected
org.apache.logging.log4j:log4j-api 2.13.1 2.25.5 unbounded
org.apache.logging.log4j:log4j-api 2.26.0 2.26.1 unbounded

Products and versions

2 products, 9 version entries
SourceVendorProductSchemeAffected versions
nvd apache log4j generic ≥ 2.13.1 and ＜ 2.25.5 · 2.26.0 · 3.0.0:alpha1 · 3.0.0:alpha1_rc1 · 3.0.0:alpha1_rc2 · 3.0.0:beta1 · 3.0.0:beta2
osv org.apache.logging.log4j log4j-api generic ≥ 2.13.1 and ＜ 2.25.5 · ≥ 2.26.0 and ＜ 2.26.1

References

URLTags
https://github.com/apache/logging-log4j2/pull/4163 pr
https://github.com/apache/logging-log4j2/commit/19edb23e162d6c728a8c2221a240037d389ed300 WEB
https://github.com/apache/logging-log4j2/commit/feadf8eb0b4acb6ddfa4c0ab2bbc6d88b8e12d82 WEB
https://github.com/apache/logging-log4j2 PACKAGE
https://github.com/apache/logging-log4j2/releases/tag/rel/2.25.5 WEB
https://github.com/apache/logging-log4j2/releases/tag/rel/2.26.1 WEB
https://logging.apache.org/cyclonedx/vdr.xml WEB
https://logging.apache.org/log4j/2.x/manual/json-template-layout.html#event-template-resolver-message WEB
https://logging.apache.org/security.html#CVE-2026-49844 WEB

Timeline
Published2026-07-10By the CVE Program.
NVD record modified2026-10-25NVD's own last-modified date for this record.