CVE-2020-29484

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Summary

CVECVE-2020-29484
StatePUBLIC
Assigner[email protected]
Source PriorityCVE Program / NVD first with legacy fallback
Published2020-12-15 18:15:00 UTC
Updated2023-11-07 03:21:00 UTC
DescriptionAn issue was discovered in Xen through 4.14.x. When a Xenstore watch fires, the xenstore client that registered the watch will receive a Xenstore message containing the path of the modified Xenstore entry that triggered the watch, and the tag that was specified when registering the watch. Any communication with xenstored is done via Xenstore messages, consisting of a message header and the payload. The payload length is limited to 4096 bytes. Any request to xenstored resulting in a response with a payload longer than 4096 bytes will result in an error. When registering a watch, the payload length limit applies to the combined length of the watched path and the specified tag. Because watches for a specific path are also triggered for all nodes below that path, the payload of a watch event message can be longer than the payload needed to register the watch. A malicious guest that registers a watch using a very large tag (i.e., with a registration operation payload length close to the 4096 byte limit) can cause the generation of watch events with a payload length larger than 4096 bytes, by writing to Xenstore entries below the watched path. This will result in an error condition in xenstored. This error can result in a NULL pointer dereference, leading to a crash of xenstored. A malicious guest administrator can cause xenstored to crash, leading to a denial of service. Following a xenstored crash, domains may continue to run, but management operations will be impossible. Only C xenstored is affected, oxenstored is not affected.

Risk And Classification

Problem Types: CWE-476

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Debian Debian Linux 10.0 All All All
Operating System Debian Debian Linux 10.0 All All All
Operating System Fedoraproject Fedora 32 All All All
Operating System Fedoraproject Fedora 33 All All All
Operating System Xen Xen All All All All

References

ReferenceSourceLinkTags
xenbits.xenproject.org/xsa/advisory-324.txt MISC xenbits.xenproject.org Patch, Vendor Advisory
Debian -- Security Information -- DSA-4812-1 xen DEBIAN www.debian.org Third Party Advisory
[SECURITY] Fedora 33 Update: xen-4.14.0-14.fc33 - package-announce - Fedora Mailing-Lists lists.fedoraproject.org
[SECURITY] Fedora 32 Update: xen-4.13.2-5.fc32 - package-announce - Fedora Mailing-Lists FEDORA lists.fedoraproject.org Mailing List, Third Party Advisory
[SECURITY] Fedora 32 Update: xen-4.13.2-5.fc32 - package-announce - Fedora Mailing-Lists lists.fedoraproject.org
[SECURITY] Fedora 33 Update: xen-4.14.0-14.fc33 - package-announce - Fedora Mailing-Lists FEDORA lists.fedoraproject.org Mailing List, Third Party Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Legacy QID Mappings

  • 500796 Alpine Linux Security Update for xen
  • 501515 Alpine Linux Security Update for xen
  • 504539 Alpine Linux Security Update for xen
  • 750465 OpenSUSE Security Update for xen (openSUSE-SU-2020:2331-1)
  • 750474 OpenSUSE Security Update for xen (openSUSE-SU-2020:2313-1)
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