GHSA-rv64-5gf8-9qq8: org.apache.tomcat:tomcat-catalina (CVE-2026-34483)

Apache Tomcat has an Improper Encoding or Escaping of Output vulnerability in the JsonAccessLogValve

CVSS 7.5 HighEPSS 0.0047 · 40th percentile

Published by the GitHub Advisory Database at 9 Apr 2026, 21:31 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

Package	Ecosystem	Affected	Fixed in
org.apache.tomcat:tomcat-catalina	Maven	>=9.0.40, <9.0.116 \|\| >=10.1.0-M1, <10.1.54 \|\| >=11.0.0-M1, <11.0.21	9.0.116, 10.1.54, 11.0.21
org.apache.tomcat:tomcat	Maven	>=9.0.40, <9.0.116 \|\| >=10.1.0-M1, <10.1.54 \|\| >=11.0.0-M1, <11.0.21	9.0.116, 10.1.54, 11.0.21
org.apache.tomcat.embed:tomcat-embed-core	Maven	>=9.0.40, <9.0.116 \|\| >=10.1.0-M1, <10.1.54 \|\| >=11.0.0-M1, <11.0.21	9.0.116, 10.1.54, 11.0.21

Identifiers

GHSA-rv64-5gf8-9qq8 · BIT-tomcat-2026-34483 · CVE-2026-34483

Weakness (CWE)

CWE-116

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Apache Tomcat 9.0.40 to 9.0.116, 10.1.0-M1 to 10.1.53, and 11.0.0-M1 to 11.0.20 have improper encoding or escaping of output in the JsonAccessLogValve component. The source gives few details on attacker requirements or impact. Upgrade to 11.0.21, 10.1.54, or 9.0.117 (the package data lists 9.0.116 as fixed for 9.0).

Written 2 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
7.5	High	3.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N	GitHub Advisory Database

CISA KEV Not listed.
EPSS 0.0047, the 40th percentile, on 7 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 14:16 UTC First seen by agentprime
31 Oct 2026, 14:16 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.