NULL Pointer Dereference Affecting mod_ssl package, versions <1:2.4.46-2.amzn2


Severity

Recommended
0.0
high
0
10

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
51.49% (99th percentile)

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  • Snyk IDSNYK-AMZN2-MODSSL-1701375
  • published27 Sept 2021
  • disclosed15 Jun 2021

Introduced: 15 Jun 2021

CVE-2021-31618  (opens in a new tab)
CWE-476  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2 mod_ssl to version 1:2.4.46-2.amzn2 or higher.
This issue was patched in ALAS2-2021-1672.

NVD Description

Note: Versions mentioned in the description apply only to the upstream mod_ssl package and not the mod_ssl package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2 relevant fixed versions and status.

Apache HTTP Server protocol handler for the HTTP/2 protocol checks received request headers against the size limitations as configured for the server and used for the HTTP/1 protocol as well. On violation of these restrictions and HTTP response is sent to the client with a status code indicating why the request was rejected. This rejection response was not fully initialised in the HTTP/2 protocol handler if the offending header was the very first one received or appeared in a a footer. This led to a NULL pointer dereference on initialised memory, crashing reliably the child process. Since such a triggering HTTP/2 request is easy to craft and submit, this can be exploited to DoS the server. This issue affected mod_http2 1.15.17 and Apache HTTP Server version 2.4.47 only. Apache HTTP Server 2.4.47 was never released.

References

CVSS Base Scores

version 3.1