CVE-2026-34483 | Apache Tomcat: Incomplete escaping of JSON access logs

Improper Encoding or Escaping of Output vulnerability in the JsonAccessLogValve component of Apache Tomcat. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.20, from 10.1.0-M1 through 10.1.53, from 9.0.40 through 9.0.116. Users are recommended to upgrade to version 11.0.21, 10.1.54 or 9.0.117 , which fix the issue.

Published: 2026-04-09 Last update: 2026-04-14 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-34483 is rated Low Risk (38.5/100): CVSS High severity, with low exploitation likelihood (EPSS 0.08%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-34483

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-15 0.02% 0.08% +0.06%
2 2026-04-10 — 0.02% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-34483

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2026-34483

GitHub Security Advisory for CVE-2026-34483

GHSA-rv64-5gf8-9qq8 · Severity: high · Ecosystem: maven — Apache Tomcat has an Improper Encoding or Escaping of Output vulnerability in the JsonAccessLogValve

OS Trackers for CVE-2026-34483

vendor priority summary link
debian not yet assigned CVE-2026-34483 not yet assigned priority: Debian including 3 source packages (tomcat10, tomcat11, tomcat9), 12 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 12. https://security-tracker.debian.org/tracker/CVE-2026-34483
redhat low — https://access.redhat.com/security/cve/CVE-2026-34483
suse medium CVE-2026-34483 severity moderate: SUSE including 34 source package names (tomcat, tomcat-9.0.117-1.1, …), 34 product×package rows across 2 product lines (SUSE Linux Enterprise Server Teradata 12 SP3, openSUSE Tumbleweed): Fixed 33, Known Not Affected 1. https://www.suse.com/security/cve/CVE-2026-34483/
ubuntu medium CVE-2026-34483 medium priority: Ubuntu including 6 source packages (tomcat10, tomcat11, tomcat6, tomcat7, tomcat8, tomcat9), 33 status rows across 8 suites (bionic, focal, jammy, noble, questing, trusty, upstream, xenial): needs-triage 18, DNE 12, ignored 3. https://ubuntu.com/security/CVE-2026-34483

Affected software / configurations for CVE-2026-34483

Vendor Product Version Raw CPE
apache tomcat >= 9.0.40, < 9.0.117 cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*
apache tomcat >= 10.1.0, < 10.1.54 cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*
apache tomcat >= 11.0.0, < 11.0.21 cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*

References for CVE-2026-34483

cvelogic Threat Intelligence