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Vulnerability record · CVE-2020-1935 · published 24 February 2020

CVE-2020-1935: Apache tomcat http request smuggling vulnerability

Apache · 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.

4.8 CVSS 3.1 Medium EPSS 9.4% · top 4.8% CWE-444 · HTTP request smuggling
4.8CVSS 3.1 base score, v2 5.8
9.4%EPSS exploitation probability, 30 days
NoNot in CISA KEV
20Affected product versions listed by NVD
38References
17 Jun 2026Last modified by NVD

Description

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.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

Affected products

20 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00025.html Broken LinkMailing ListThird Party Advisory
https://lists.apache.org/thread.html/r127f76181aceffea2bd4711b03c595d0f115f63e020348fe925a916c%40%3Cannounce.tomcat.apac Mailing ListVendor Advisory
https://lists.apache.org/thread.html/r441c1f30a252bf14b07396286f6abd8089ce4240e91323211f1a2d75%40%3Cusers.tomcat.apache.
https://lists.apache.org/thread.html/r660cd379afe346f10d72c0eaa8459ccc95d83aff181671b7e9076919%40%3Cusers.tomcat.apache.
https://lists.apache.org/thread.html/r7bc994c965a34876bd94d5ff15b4e1e30b6220a15eb9b47c81915b78%40%3Ccommits.tomee.apache
https://lists.apache.org/thread.html/r80e9c8417c77d52c62809168b96912bda70ddf7748f19f8210f745b1%40%3Cusers.tomcat.apache.
https://lists.apache.org/thread.html/r9ce7918faf347e7aac32be930bf26c233b0b140fe37af0bb294158b6%40%3Cdev.tomcat.apache.or
https://lists.apache.org/thread.html/ra5dee390ad2d60307b8362505c059cd6a726de4d146d63dfce1e05e7%40%3Cusers.tomcat.apache.
https://lists.apache.org/thread.html/rc31cbabb46cdc58bbdd8519a8f64b6236b2635a3922bbeba0f0e3743%40%3Ccommits.tomee.apache
https://lists.apache.org/thread.html/rd547be0c9d821b4b1000a694b8e58ef9f5e2d66db03a31dfe77c4b18%40%3Cusers.tomcat.apache.
https://lists.debian.org/debian-lts-announce/2020/03/msg00006.html Mailing ListThird Party Advisory
https://lists.debian.org/debian-lts-announce/2020/05/msg00026.html Mailing ListThird 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
http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00025.html Broken LinkMailing ListThird Party Advisory
https://lists.apache.org/thread.html/r127f76181aceffea2bd4711b03c595d0f115f63e020348fe925a916c%40%3Cannounce.tomcat.apac Mailing ListVendor Advisory
https://lists.apache.org/thread.html/r441c1f30a252bf14b07396286f6abd8089ce4240e91323211f1a2d75%40%3Cusers.tomcat.apache.
https://lists.apache.org/thread.html/r660cd379afe346f10d72c0eaa8459ccc95d83aff181671b7e9076919%40%3Cusers.tomcat.apache.
https://lists.apache.org/thread.html/r7bc994c965a34876bd94d5ff15b4e1e30b6220a15eb9b47c81915b78%40%3Ccommits.tomee.apache
https://lists.apache.org/thread.html/r80e9c8417c77d52c62809168b96912bda70ddf7748f19f8210f745b1%40%3Cusers.tomcat.apache.
https://lists.apache.org/thread.html/r9ce7918faf347e7aac32be930bf26c233b0b140fe37af0bb294158b6%40%3Cdev.tomcat.apache.or
https://lists.apache.org/thread.html/ra5dee390ad2d60307b8362505c059cd6a726de4d146d63dfce1e05e7%40%3Cusers.tomcat.apache.
https://lists.apache.org/thread.html/rc31cbabb46cdc58bbdd8519a8f64b6236b2635a3922bbeba0f0e3743%40%3Ccommits.tomee.apache
https://lists.apache.org/thread.html/rd547be0c9d821b4b1000a694b8e58ef9f5e2d66db03a31dfe77c4b18%40%3Cusers.tomcat.apache.
https://lists.debian.org/debian-lts-announce/2020/03/msg00006.html Mailing ListThird Party Advisory
https://lists.debian.org/debian-lts-announce/2020/05/msg00026.html Mailing ListThird 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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Source: NIST National Vulnerability Database (record CVE-2020-1935), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.