CVE-2020-1935

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: 2020-02-24 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2020-1935 is rated Moderate Risk (47.6/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 1.37%). Mandatory action: Review affected assets and schedule remediation.

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-2020-1935

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 2026-03-28 1.01% 1.37% +0.36%
2 2026-03-04 0.51% 1.01% +0.50%
3 2026-03-01 0.51%

Full EPSS history (44 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-1935

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.8 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/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:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
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:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
2.2 2.5 [email protected]
5.8 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
8.6 4.9 [email protected]

Weakness enumeration for CVE-2020-1935

GitHub Security Advisory for CVE-2020-1935

GHSA-qxf4-chvg-4r8r · Severity: medium · Ecosystem: maven — Potential HTTP request smuggling in Apache Tomcat

OS Trackers for CVE-2020-1935

vendor priority summary link
debian not yet assigned CVE-2020-1935 not yet assigned priority: Debian including 1 source packages (tomcat9), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2020-1935
redhat low https://access.redhat.com/security/cve/CVE-2020-1935
ubuntu low CVE-2020-1935 low priority: Ubuntu including 3 source packages (tomcat7, tomcat8, tomcat9), 51 status rows across 17 suites (bionic, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 29, not-affected 12, needed 5, released 4, ignored 1. https://ubuntu.com/security/CVE-2020-1935

Affected software / configurations for CVE-2020-1935

Vendor Product Version Raw CPE
apache tomcat >= 7.0.0, <= 7.0.99 cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*
apache tomcat >= 8.5.0, <= 8.5.50 cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*
apache tomcat >= 9.0.0, <= 9.0.30 cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:-:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone1:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone10:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone11:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone12:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone13:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone14:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone15:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone16:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone17:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone18:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone19:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone2:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone20:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone21:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone22:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone23:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone24:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone25:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone26:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone27:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone3:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone4:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone5:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone6:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone7:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone8:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone9:*:*:*:*:*:*
debian debian_linux 8.0 cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
canonical ubuntu_linux 16.04 cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
opensuse leap 15.1 cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:*
netapp data_availability_services cpe:2.3:a:netapp:data_availability_services:-:*:*:*:*:*:*:*
netapp oncommand_system_manager >= 3.0.0, <= 3.1.3 cpe:2.3:a:netapp:oncommand_system_manager:*:*:*:*:*:*:*:*
oracle agile_engineering_data_management 6.2.1.0 cpe:2.3:a:oracle:agile_engineering_data_management:6.2.1.0:*:*:*:*:*:*:*
oracle agile_product_lifecycle_management 9.3.3 cpe:2.3:a:oracle:agile_product_lifecycle_management:9.3.3:*:*:*:*:*:*:*
oracle agile_product_lifecycle_management 9.3.5 cpe:2.3:a:oracle:agile_product_lifecycle_management:9.3.5:*:*:*:*:*:*:*
oracle agile_product_lifecycle_management 9.3.6 cpe:2.3:a:oracle:agile_product_lifecycle_management:9.3.6:*:*:*:*:*:*:*
oracle communications_element_manager 8.1.1 cpe:2.3:a:oracle:communications_element_manager:8.1.1:*:*:*:*:*:*:*
oracle communications_element_manager 8.2.0 cpe:2.3:a:oracle:communications_element_manager:8.2.0:*:*:*:*:*:*:*
oracle communications_element_manager 8.2.1 cpe:2.3:a:oracle:communications_element_manager:8.2.1:*:*:*:*:*:*:*
oracle communications_instant_messaging_server 10.0.1.4.0 cpe:2.3:a:oracle:communications_instant_messaging_server:10.0.1.4.0:*:*:*:*:*:*:*
oracle health_sciences_empirica_inspections 1.0.1.2 cpe:2.3:a:oracle:health_sciences_empirica_inspections:1.0.1.2:*:*:*:*:*:*:*
oracle health_sciences_empirica_signal 7.3.3 cpe:2.3:a:oracle:health_sciences_empirica_signal:7.3.3:*:*:*:*:*:*:*
oracle hospitality_guest_access 4.2.0 cpe:2.3:a:oracle:hospitality_guest_access:4.2.0:*:*:*:*:*:*:*
oracle hospitality_guest_access 4.2.1 cpe:2.3:a:oracle:hospitality_guest_access:4.2.1:*:*:*:*:*:*:*
oracle hyperion_infrastructure_technology 11.1.2.4 cpe:2.3:a:oracle:hyperion_infrastructure_technology:11.1.2.4:*:*:*:*:*:*:*
oracle instantis_enterprisetrack >= 17.1, <= 17.3 cpe:2.3:a:oracle:instantis_enterprisetrack:*:*:*:*:*:*:*:*
oracle mysql_enterprise_monitor >= 4.0.0, <= 4.0.12 cpe:2.3:a:oracle:mysql_enterprise_monitor:*:*:*:*:*:*:*:*
oracle mysql_enterprise_monitor >= 8.0.0, <= 8.0.20 cpe:2.3:a:oracle:mysql_enterprise_monitor:*:*:*:*:*:*:*:*
oracle retail_order_broker 15.0 cpe:2.3:a:oracle:retail_order_broker:15.0:*:*:*:*:*:*:*
oracle siebel_ui_framework <= 20.5 cpe:2.3:a:oracle:siebel_ui_framework:*:*:*:*:*:*:*:*
oracle transportation_management 6.3.7 cpe:2.3:a:oracle:transportation_management:6.3.7:*:*:*:*:*:*:*
oracle workload_manager 12.2.0.1 cpe:2.3:a:oracle:workload_manager:12.2.0.1:*:*:*:*:*:*:*
oracle workload_manager 18c cpe:2.3:a:oracle:workload_manager:18c:*:*:*:*:*:*:*
oracle workload_manager 19c cpe:2.3:a:oracle:workload_manager:19c:*:*:*:*:*:*:*

References for CVE-2020-1935

URL Tags
http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00025.html Broken Link Mailing List Third Party Advisory
https://lists.apache.org/thread.html/r127f76181aceffea2bd4711b03c595d0f115f63e020348fe925a916c%40%3Cannounce.tomcat.apache.org%3E Mailing List Vendor Advisory
https://lists.apache.org/thread.html/r441c1f30a252bf14b07396286f6abd8089ce4240e91323211f1a2d75%40%3Cusers.tomcat.apache.org%3E
https://lists.apache.org/thread.html/r660cd379afe346f10d72c0eaa8459ccc95d83aff181671b7e9076919%40%3Cusers.tomcat.apache.org%3E
https://lists.apache.org/thread.html/r7bc994c965a34876bd94d5ff15b4e1e30b6220a15eb9b47c81915b78%40%3Ccommits.tomee.apache.org%3E
https://lists.apache.org/thread.html/r80e9c8417c77d52c62809168b96912bda70ddf7748f19f8210f745b1%40%3Cusers.tomcat.apache.org%3E
https://lists.apache.org/thread.html/r9ce7918faf347e7aac32be930bf26c233b0b140fe37af0bb294158b6%40%3Cdev.tomcat.apache.org%3E
https://lists.apache.org/thread.html/ra5dee390ad2d60307b8362505c059cd6a726de4d146d63dfce1e05e7%40%3Cusers.tomcat.apache.org%3E
https://lists.apache.org/thread.html/rc31cbabb46cdc58bbdd8519a8f64b6236b2635a3922bbeba0f0e3743%40%3Ccommits.tomee.apache.org%3E
https://lists.apache.org/thread.html/rd547be0c9d821b4b1000a694b8e58ef9f5e2d66db03a31dfe77c4b18%40%3Cusers.tomcat.apache.org%3E
https://lists.debian.org/debian-lts-announce/2020/03/msg00006.html Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/05/msg00026.html Mailing List Third Party Advisory
https://security.netapp.com/advisory/ntap-20200327-0005/ Third Party Advisory
https://usn.ubuntu.com/4448-1/ Third Party Advisory
https://www.debian.org/security/2020/dsa-4673 Third Party Advisory
https://www.debian.org/security/2020/dsa-4680 Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2021.html Third Party Advisory
https://www.oracle.com/security-alerts/cpujul2020.html Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2020.html Third Party Advisory
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