CVE-2026-49844

MEDIUMNVD 5.95.9—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.9 under NVD CVSS v3. EPSS exploit probability: 0.7%, top 52% 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
5.9
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 1%CVSS: 5.9Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
5.9
EG Score
5.9(medium)
EG Risk
27(Track)
EG Risk 27/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity59% × 45%
Exploitation1% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
47.7%
KEV
Not listed

Published

July 10, 2026

Last Modified

July 14, 2026

Advisory Details (4)

Auto-updated Jul 10, 2026
Patch available. Sources: github_pr.
generic Patch Available

Security :: Apache Logging Services

https://logging.apache.org/security.html#CVE-2026-49844
generic

JSON Template Layout :: Apache Log4j

https://logging.apache.org/log4j/2.x/manual/json-template-layout.html#event-template-resolver-message
generic Patch Available
https://logging.apache.org/cyclonedx/vdr.xml
github_pr

Fix handling of non-finite numbers while encoding `MapMessage` to JSON

Fix merged in apache/logging-log4j2 PR #4163 on 2026-06-29 — awaiting tagged release

https://github.com/apache/logging-log4j2/pull/4163

Vendor Advisories for CVE-2026-49844(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 10× in last 7d / 26× 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.

  1. 2026-07-23 14:18 UTCEPSS rescore
  2. 2026-07-23 03:18 UTCEG score recompute
  3. 2026-07-22 14:08 UTCEPSS rescore
  4. 2026-07-21 15:25 UTCEPSS rescore
  5. 2026-07-20 17:08 UTCEPSS rescore
  6. 2026-07-19 14:31 UTCEPSS rescore
  7. 2026-07-19 14:31 UTCEPSS rescore
  8. 2026-07-19 02:29 UTCEPSS rescore
  9. 2026-07-18 10:04 UTCEPSS rescore
  10. 2026-07-17 00:27 UTCGHSA enrichment
  11. 2026-07-16 17:03 UTCEPSS rescore
  12. 2026-07-15 23:58 UTCGHSA enrichment
  13. 2026-07-15 16:57 UTCEPSS rescore
  14. 2026-07-15 16:57 UTCEPSS rescore
  15. 2026-07-15 02:00 UTCEPSS rescore
  16. 2026-07-14 23:29 UTCEG score recompute▼ 0.40
  17. 2026-07-14 23:29 UTCGHSA enrichment
  18. 2026-07-14 20:04 UTCNVD updateCVSS v3 → 5.9
  19. 2026-07-13 23:00 UTCGHSA enrichment
  20. 2026-07-13 22:30 UTCEPSS rescore
  21. 2026-07-13 06:13 UTCEPSS rescore
  22. 2026-07-12 22:31 UTCGHSA enrichment
  23. 2026-07-12 05:46 UTCEPSS rescore
  24. 2026-07-11 22:02 UTCGHSA enrichment
  25. 2026-07-10 21:33 UTCEG score recompute
Show 1 more
  1. 2026-07-10 21:32 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-49844?
CVE-2026-49844 is a medium vulnerability published on July 10, 2026. 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…
When was CVE-2026-49844 disclosed?
CVE-2026-49844 was first published in the National Vulnerability Database on July 10, 2026, with the most recent update on July 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-49844 actively exploited?
CVE-2026-49844 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 47.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-49844?
CVE-2026-49844 has a CVSS v3 base score of 5.9 (NVD).
How do I remediate CVE-2026-49844?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-49844, 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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