CVE Intelligence
Medium Injection

CVE-2020-1935 — HTTP Request Smuggling in Apache Software Foundation Tomcat

In Apache Tomcat 9.0.0.M1 to 9.0.30, 8.5.0 to 8.5.50 and 7.0.0 to 7.0.99 the HTTP header parsing code used an approach to end-of-line parsing that allowed some invalid HTTP headers to be parsed as valid. This led to a possibility of HTTP Request Smuggling if Tomcat was located behind a reverse proxy that incorrectly handled the invalid Transfer-Encoding header in a particular manner. Such a reverse proxy is considered unlikely.

Published Feb 24, 2020 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: apache

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 9.4% (30-day exploitation probability)+14
  • Technical severity (medium)+3
  • Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
9.39%
ahead of 95% of scored CVEs · Oct 14, 2026
Affects
Apache Software Foundation
Tomcat and 19 more
CVSS base
4.8
Medium · 1 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
Yes
can an attacker script the kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Apache Software Foundation Tomcat, Canonical Ubuntu Linux, Debian Debian Linux…).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  4. EPSS ahead of 95% of scored CVEs: prioritize it in the patch queue.
  5. Search available logs for exploit probes matching the vulnerability class (injection), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Apache Software Foundation Tomcat version 9.0.0-milestone24version 9.0.0-milestone17version 9.0.0-milestone18version 9.0.0-milestone19version 9.0.0-milestone2version 9.0.0-milestone20version 9.0.0-milestone21version 9.0.0-milestone22
and 23 more version 9.0.0-milestone23version 9.0.0-milestone16version 9.0.0-milestone25version 9.0.0-milestone26version 9.0.0-milestone27version 9.0.0-milestone3version 9.0.0-milestone4version 9.0.0-milestone5version 9.0.0-milestone6version 9.0.0-milestone7≥ 9.0.0 and ≤ 9.0.30version 9.0.0-milestone9version 9.0.0-milestone8≥ 7.0.0 and ≤ 7.0.99≥ 8.5.0 and ≤ 8.5.50version 9.0.0version 9.0.0-milestone1version 9.0.0-milestone10version 9.0.0-milestone11version 9.0.0-milestone12version 9.0.0-milestone13version 9.0.0-milestone14version 9.0.0-milestone15
Vulnerable NIST National Vulnerability Database
Apache Software Foundation Tomcat version 7.0.0 to 7.0.99version 8.5.0 to 8.5.50version Apache Tomcat 9.0.0.M1 to 9.0.30 Vulnerable CVE Program (cve.org) e CISA ADP
Canonical Ubuntu Linux version 16.04 Vulnerable NIST National Vulnerability Database
Debian Debian Linux version 9.0version 10.0version 8.0 Vulnerable NIST National Vulnerability Database
Netapp Data Availability Services versions not specified by the source Vulnerable NIST National Vulnerability Database
Netapp Oncommand System Manager ≥ 3.0.0 and ≤ 3.1.3 Vulnerable NIST National Vulnerability Database
Opensuse Leap version 15.1 Vulnerable NIST National Vulnerability Database
Oracle Agile Engineering Data Management version 6.2.1.0 Vulnerable NIST National Vulnerability Database
Oracle Agile Product Lifecycle Management version 9.3.5version 9.3.3version 9.3.6 Vulnerable NIST National Vulnerability Database
Oracle Communications Element Manager version 8.1.1version 8.2.0version 8.2.1 Vulnerable NIST National Vulnerability Database
Oracle Communications Instant Messaging Server version 10.0.1.4.0 Vulnerable NIST National Vulnerability Database
Oracle Health Sciences Empirica Inspections version 1.0.1.2 Vulnerable NIST National Vulnerability Database
Oracle Health Sciences Empirica Signal version 7.3.3 Vulnerable NIST National Vulnerability Database
Oracle Hospitality Guest Access version 4.2.0version 4.2.1 Vulnerable NIST National Vulnerability Database
Oracle Hyperion Infrastructure Technology version 11.1.2.4 Vulnerable NIST National Vulnerability Database
Oracle Instantis Enterprisetrack ≥ 17.1 and ≤ 17.3 Vulnerable NIST National Vulnerability Database
Oracle Mysql Enterprise Monitor ≥ 8.0.0 and ≤ 8.0.20≥ 4.0.0 and ≤ 4.0.12 Vulnerable NIST National Vulnerability Database
Oracle Retail Order Broker version 15.0 Vulnerable NIST National Vulnerability Database
Oracle Siebel Ui Framework ≤ 20.5 Vulnerable NIST National Vulnerability Database
Oracle Transportation Management version 6.3.7 Vulnerable NIST National Vulnerability Database
Oracle Workload Manager version 12.2.0.1version 18cversion 19c Vulnerable NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
4.8 CVSS 3.1 Medium 2.2 2.5 nvd@nist.gov via NIST National Vulnerability Database
5.8 CVSS 2.0 Medium 8.6 4.9 nvd@nist.gov via NIST National Vulnerability Database
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-444 · HTTP Request Smuggling

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 9.39%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Look for parameters with command/query metacharacters and unexpected child processes of the service.
web/proxy/WAF logsnetwork IDS/IPSapplication logsendpoint telemetry (EDR)

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · apache/apache tomcat
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 13, 2026
  • CVSS changed · 4.8
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · → Modified
    Oct 13, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 13, 2026 · NIST National Vulnerability Database
  • 2020
  • CVE published
    Feb 24, 2020 · apache

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

19 on the record

Elsewhere on this site

Apache Software Foundation
every CVE for this vendor
Injection
same class
CWE-444
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-12996 A use-after-free in OpenVPN 2.6.0 through 2.6.20 and 2.7_alpha1 through 2.7.4 allows remote... Jul 30, 2026
  • CVE-2026-66299 Uncontrolled Resource Consumption in Apache Software Foundation Tomcat Jul 28, 2026
  • CVE-2026-61195 Uncontrolled Resource Consumption in Oracle Agile Engineering Data Management Jul 21, 2026
  • CVE-2026-61191 Improper Access Control in Oracle Agile Engineering Data Management Jul 21, 2026
  • CVE-2026-61192 Uncontrolled Resource Consumption in Oracle Agile Engineering Data Management Jul 21, 2026
  • CVE-2026-61194 Uncontrolled Resource Consumption in Oracle Agile Engineering Data Management Jul 21, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2020-1935 is "HTTP Request Smuggling in Apache Software Foundation Tomcat", rated Medium. It affects Tomcat (Apache Software Foundation); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 4.8 describes technical severity. EPSS 9.39% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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