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Full vulnerability report · 2026
CVE-2026-59083High confidence

Apache Tomcat: Incorrect URL decoding in RewriteValve may allow security control bypass

Apache Software Foundation · Apache Tomcat

9.1CriticalCVSS 3.1
Recommended action
Within 72 hours

Critical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded.

Patch available
Distribution package intelligence

Ubuntu vendor package status

Canonical’s release and source-package findings are shown separately from local repository availability.

2 package states
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Ubuntu releaseSource packageVendor stateFixed versionEvidence
Ubuntu 24.04 LTSnoble · esm-appstomcat10Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical record ↗Source updated 11 Sept 2026
Ubuntu 24.04 LTSnoble · esm-appstomcat9Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical record ↗Source updated 11 Sept 2026
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-43638

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 72 hours

Critical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded.

Patch available
01

What, why and how

Improper Handling of URL Encoding (Hex Encoding) vulnerability in Apache Tomcat's rewrite valve allowed security constraint bypass for some configurations. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.23, from 10.1.0-M1 through 10.1.56, from 9.0.0.M1 through 9.0.119, from 8.5.0 through 8.5.100. Other versions that have reached end of support may also be affected. Users are recommended to upgrade to version 11.0.24, 10.1.57 or 9.0.120, which fix the issue.

What

Improper Handling of URL Encoding (Hex Encoding) vulnerability in Apache Tomcat's rewrite valve allowed security constraint bypass for some configurations. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.23, from 10.1.0-M1 through 10.1.56, from 9.0.0.M1 through 9.0.119, from 8.5.0 through 8.5.100. Other versions that have reached end of support may also be affected. Users are recommended to upgrade to version 11.0.24, 10.1.57 or 9.0.120, which fix the issue.

Why

The product does not properly handle when all or part of an input has been URL encoded.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Improper Handling of URL Encoding (Hex Encoding) vulnerability in Apache Tomcat's rewrite valve allowed security constraint bypass for some configurations. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.23, from 10.1.0-M1 through 10.1.56, from 9.0.0.M1 through 9.0.119, from 8.5.0 through 8.5.100. Other versions that have reached end of support may also be affected. Users are recommended to upgrade to version 11.0.24, 10.1.57 or 9.0.120, which fix the issue.

Why

The product does not properly handle when all or part of an input has been URL encoded.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Improper Handling of URL Encoding (Hex Encoding) → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-177 ↗

CWE-177: Improper Handling of URL Encoding (Hex Encoding). The product does not properly handle when all or part of an input has been URL encoded.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.ANoneAvailability impact: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-177
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-W-2026-3043IBM QRadar SIEM: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in IBM QRadar SIEM ausnutzen, um Sicherheitsvorkehrungen zu umgehen, um seine Privilegien zu erhöhen, um einen Denial of Service Angriff durchzuführen, um Informationen offenzulegen, um Dateien zu manipulieren, um einen Cross-Site Scripting Angriff durchzuführen und um beliebigen Programmcode auszuführen.

Official advisory
BSI · German · WID-SEC-W-2026-2310Apache Tomcat: Mehrere Schwachstellen

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Apache Tomcat ausnutzen, um Sicherheitsvorkehrungen zu umgehen und Informationen offenzulegen.

Official advisory
CERT-FR · French · CERTFR-2026-AVI-1094Multiples vulnérabilités dans les produits IBM

d?id=CVE-2026-55693 Référence CVE CVE-2026-55798 https://www.cve.org/CVERecord?id=CVE-2026-55798 Référence CVE CVE-2026-55955 https://www.cve.org/CVERecord?id=CVE-2026-55955 Référence CVE CVE-2026-55956 https://www.cve.org/CVERecord?id=CVE-2026-55956 Référence CVE CVE-2026-56852 https://www.cve.org/CVERecord?id=CVE-2026-56852 Référence CVE CVE-2026-57455 https://www.cve.org/CVERecord?id=CVE-2026-57455 Référence CVE CVE-2026-57456 https://www.cve.org/CVERecord?id=CVE-2026-57456 Référence CVE CVE-2026-57819 https://www.cve.org/CVERecord?id=CVE-2026-57819 Référence CVE CVE-2026-58016 https://www.cve.org/CVERecord?id=CVE-2026-58016 Référence CVE CVE-2026-59083 https://www.cve.org/CVERecord?id=CVE-2026-59083 Référence CVE CVE-2026-59084 https://www.cve.org/CVERecord?id=CVE-2026-59084 Référence CVE CVE-2026-59197 https://www.cve.org/CVERecord?id=CVE-2026-59197 Référence CVE CVE-2026-59198 https://www.cve.org/CVERecord?id=CVE-2026-59198 Référence CVE CVE-2026-59199 https://www.cve.org/CVERecord?id=CVE-2026-59199 Référence CVE CVE-2026-59200 https://www.cve.org/CVERecord?id=CVE-2026-59200 Référence CVE CVE-2026-59203 https://www.cve.org/CVERecord?id=CVE-2026-59203 Référence CVE CVE-2026-59204 https://www.cve.org/CVERecord?id=CVE-2026-59204 Référence CVE CVE-2026-59205 https://www.cve.org/CVERecord?id=

Official advisory
CERT-FR · French · CERTFR-2026-AVI-0876Multiples vulnérabilités dans Apache Tomcat

De multiples vulnérabilités ont été découvertes dans Apache Tomcat. Elles permettent à un attaquant de provoquer un contournement de la politique de sécurité et un problème de sécurité non spécifié par l'éditeur.

Official advisory
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
11.0.0-M1 ≤ 11.0.23; 10.1.0-M1 ≤ 10.1.56; 9.0.0.M1 ≤ 9.0.119; 8.5.0 ≤ 8.5.100
Fixed
< 8.0.0
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
A mitigation or workaround reference is available from the source linked below; validate it against the affected product and version.
04

Evidence and provenance

Published 14 Jul 2026 · Last source change 14 Jul 2026, 12:19 UTC · CWE-177 · Improper Handling of URL Encoding (Hex Encoding)

CVE recordCVE.org · 5.2
CVSS sourceCISA ADP
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2026-43638
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates →

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2026-43638↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-59083 · cve.blacktree.nl