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CVE-2019-16785

HIGHCVSS 7.5/10EPSS 2.71%

Last modified

CVE-2019-16785 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. Waitress through version 1.3.1 implemented a "MAY" part of the RFC7230 which states: "Although the line terminator for the start-line and header fields is the sequence CRLF, a recipient MAY recognize a single LF as a line terminator and ignore any preceding CR." Unfortunately if a front-end server does not parse header fields with an LF the same way as it does those with a CRLF it can lead to the front-end and the back-end server parsing the same HTTP message in two different ways. This can lead to a potential for HTTP request smuggling/splitting whereby Waitress may see two requests while the front-end server only sees a single HTTP message. EPSS estimates a 2.71% chance of exploitation in the next 30 days.

Description

Waitress through version 1.3.1 implemented a "MAY" part of the RFC7230 which states: "Although the line terminator for the start-line and header fields is the sequence CRLF, a recipient MAY recognize a single LF as a line terminator and ignore any preceding CR." Unfortunately if a front-end server does not parse header fields with an LF the same way as it does those with a CRLF it can lead to the front-end and the back-end server parsing the same HTTP message in two different ways. This can lead to a potential for HTTP request smuggling/splitting whereby Waitress may see two requests while the front-end server only sees a single HTTP message. This issue is fixed in Waitress 1.4.0.

Metrics

CVSS 3.1
7.5/10

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

EPSS Probability
2.71%

84.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
AgendalessWaitress<= 1.3.1
OracleCommunications Cloud Native Core Network Function Cloud Native Environment1.10.0
DebianDebian Linux9.0
FedoraprojectFedora30
FedoraprojectFedora31
RedhatOpenstack15

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is CVE-2019-16785?
Waitress through version 1.3.1 implemented a "MAY" part of the RFC7230 which states: "Although the line terminator for the start-line and header fields is the sequence CRLF, a recipient MAY recognize a single LF as a line terminator and ignore any preceding CR." Unfortunately if a front-end server does not parse header fields with an LF the same way as it does those with a CRLF it can lead to the front-end and the back-end server parsing the same HTTP message in two different ways. This can lead to a potential for HTTP request smuggling/splitting whereby Waitress may see two requests while the front-end server only sees a single HTTP message. This issue is fixed in Waitress 1.4.0.
How severe is CVE-2019-16785?
CVE-2019-16785 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 2.71% probability of exploitation in the next 30 days.
How do I fix CVE-2019-16785?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2019-16785?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST