CVE-2021-31618
Description
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.
How to fix
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2NKJ3ZA3FTSZ2QBBPKS6BYGAWYRABNQQ/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/A73QJ4HPUMU26I6EULG6SCK67TUEXZYR/
- debian.org/security/2021/dsa-4937
- security.gentoo.org/glsa/202107-38
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| apache http_server | 1.15.17, 2.4.47 | — |
| fedoraproject fedora | 33, 34 | — |
| debian debian_linux | 9.0, 10.0 | — |
| oracle enterprise_manager_ops_center | 12.4.0.0 | — |
| oracle instantis_enterprisetrack | 17.1, 17.2, 17.3 | — |
| oracle zfs_storage_appliance_kit | 8.8 | — |
Check your version
Choose the product and enter the version you run to see whether it falls in the affected range.
Attack Surface Management
See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.