CVE-2023-46841: Recent x86 CPUs offer functionality named Control-flow Enforcement Technology (CET). A sub-feature of this are Shadow Stacks (CET-SS). CET-SS is a ha...

Description

Recent x86 CPUs offer functionality named Control-flow Enforcement Technology (CET). A sub-feature of this are Shadow Stacks (CET-SS). CET-SS is a hardware feature designed to protect against Return Oriented Programming attacks. When enabled, traditional stacks holding both data and return addresses are accompanied by so called "shadow stacks", holding little more than return addresses. Shadow stacks aren't writable by normal instructions, and upon function returns their contents are used to check for possible manipulation of a return address coming from the traditional stack. In particular certain memory accesses need intercepting by Xen. In various cases the necessary emulation involves kind of replaying of the instruction. Such replaying typically involves filling and then invoking of a stub. Such a replayed instruction may raise an exceptions, which is expected and dealt with accordingly. Unfortunately the interaction of both of the above wasn't right: Recovery involves removal of a call frame from the (traditional) stack. The counterpart of this operation for the shadow stack was missing.

Metrics

CVSS 3.1

6.5/10

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

EPSS Probability

0.27%

18.2th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Fedoraproject	Fedora	40
Xen	Xen	>= 4.14.0

References

https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/ZON4TLXG7TG4A2XZG563JMVTGQW4SF3A/Mailing List, Third Party Advisory
https://xenbits.xenproject.org/xsa/advisory-451.htmlPatch, Vendor Advisory
http://xenbits.xen.org/xsa/advisory-451.htmlPatch, Vendor Advisory
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/HES2IJXZY3H7HBPP4NVSVYYNGW254DMI/
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/ZON4TLXG7TG4A2XZG563JMVTGQW4SF3A/Mailing List, Third Party Advisory
https://xenbits.xenproject.org/xsa/advisory-451.htmlPatch, Vendor Advisory

Timeline

Published: Mar 20, 2024
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2023-46841?

Recent x86 CPUs offer functionality named Control-flow Enforcement Technology (CET). A sub-feature of this are Shadow Stacks (CET-SS). CET-SS is a hardware feature designed to protect against Return Oriented Programming attacks. When enabled, traditional stacks holding both data and return addresses are accompanied by so called "shadow stacks", holding little more than return addresses. Shadow stacks aren't writable by normal instructions, and upon function returns their contents are used to check for possible manipulation of a return address coming from the traditional stack. In particular certain memory accesses need intercepting by Xen. In various cases the necessary emulation involves kind of replaying of the instruction. Such replaying typically involves filling and then invoking of a stub. Such a replayed instruction may raise an exceptions, which is expected and dealt with accordingly. Unfortunately the interaction of both of the above wasn't right: Recovery involves removal of a call frame from the (traditional) stack. The counterpart of this operation for the shadow stack was missing.

How severe is CVE-2023-46841?

CVE-2023-46841 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.27% probability of exploitation in the next 30 days.

How do I fix CVE-2023-46841?

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.