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CVE-2021-23351

MEDIUMCVSS 4.9/10EPSS 1.87%

Last modified

CVE-2021-23351 is a medium-severity vulnerability rated 4.9/10 on the CVSS scale. The package github.com/pires/go-proxyproto before 0.5.0 are vulnerable to Denial of Service (DoS) via the parseVersion1() function. The reader in this package is a default bufio.Reader wrapping a net.Conn. EPSS estimates a 1.87% chance of exploitation in the next 30 days.

Description

The package github.com/pires/go-proxyproto before 0.5.0 are vulnerable to Denial of Service (DoS) via the parseVersion1() function. The reader in this package is a default bufio.Reader wrapping a net.Conn. It will read from the connection until it finds a newline. Since no limits are implemented in the code, a deliberately malformed V1 header could be used to exhaust memory in a server process using this code - and create a DoS. This can be exploited by sending a stream starting with PROXY and continuing to send data (which does not contain a newline) until the target stops acknowledging. The risk here is small, because only trusted sources should be allowed to send proxy protocol headers.

Metrics

CVSS 3.1
4.9/10

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

EPSS Probability
1.87%

76.7th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

VendorProductVersions
Go-Proxyproto ProjectGo-Proxyproto< 0.5.0
FedoraprojectFedora33
FedoraprojectFedora34

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is CVE-2021-23351?
The package github.com/pires/go-proxyproto before 0.5.0 are vulnerable to Denial of Service (DoS) via the parseVersion1() function. The reader in this package is a default bufio.Reader wrapping a net.Conn. It will read from the connection until it finds a newline. Since no limits are implemented in the code, a deliberately malformed V1 header could be used to exhaust memory in a server process using this code - and create a DoS. This can be exploited by sending a stream starting with PROXY and continuing to send data (which does not contain a newline) until the target stops acknowledging. The risk here is small, because only trusted sources should be allowed to send proxy protocol headers.
How severe is CVE-2021-23351?
CVE-2021-23351 has a CVSS score of 4.9/10 (MEDIUM severity). The EPSS model estimates a 1.87% probability of exploitation in the next 30 days.
How do I fix CVE-2021-23351?
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.

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Source: NVD / NIST