Vulnerability · Published Jan 6, 2022 · Assigned by XEN
CVE-2021-28715
Medium 6.5
In plain English
A medium-severity resource allocation without limits in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 30% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Guest can force Linux netback driver to hog large amounts of kernel memory T[his CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] Incoming data packets for a guest in the Linux kernel's netback driver are buffered until the guest is ready to process them. There are some measures taken for avoiding to pile up too much data, but those can be bypassed by the guest: There is a timeout how long the client side of an interface can stop consuming new packets before it is assumed to have stalled, but this timeout is rather long (60 seconds by default). Using a UDP connection on a fast interface can easily accumulate gigabytes of data in that time. (CVE-2021-28715) The timeout could even never trigger if the guest manages to have only one free slot in its RX queue ring page and the next package would require more than one free slot, which may be the case when using GSO, XDP, or software hashing. (CVE-2021-28714)
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | linux | 5.15.15-1 | DEBIAN-CVE-2021-28715 |
| Debian:13 | linux | 5.15.15-1 | DEBIAN-CVE-2021-28715 |
| Debian:14 | linux | 5.15.15-1 | DEBIAN-CVE-2021-28715 |
| Ubuntu:22.04:LTS | linux-intel-iot-realtime | no fix listed | UBUNTU-CVE-2021-28715 |
| Ubuntu:24.04:LTS | linux-raspi-realtime | no fix listed | UBUNTU-CVE-2021-28715 |
| Ubuntu:22.04:LTS | linux-realtime | no fix listed | UBUNTU-CVE-2021-28715 |
Affected products (as reported)
Weakness: CWE-770 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
References
- https://xenbits.xenproject.org/xsa/advisory-392.txt x_refsource_MISC
- DSA-5050 vendor-advisory, x_refsource_DEBIAN
- [debian-lts-announce] 20220309 [SECURITY] [DLA 2940-1] linux security update mailing-list, x_refsource_MLIST
- [debian-lts-announce] 20220309 [SECURITY] [DLA 2941-1] linux-4.19 security update mailing-list, x_refsource_MLIST
- DSA-5096 vendor-advisory, x_refsource_DEBIAN