CVE-2023-1998
MEDIUMEPSS 71th pctlDescription
The Linux kernel allows userspace processes to enable mitigations by calling prctl with PR_SET_SPECULATION_CTRL which disables the speculation feature as well as by using seccomp. We had noticed that on VMs of at least one major cloud provider, the kernel still left the victim process exposed to attacks in some cases even after enabling the spectre-BTI mitigation with prctl. The same behavior can be observed on a bare-metal machine when forcing the mitigation to IBRS on boot command line. This happened because when plain IBRS was enabled (not enhanced IBRS), the kernel had some logic that determined that STIBP was not needed. The IBRS bit implicitly protects against cross-thread branch target injection. However, with legacy IBRS, the IBRS bit was cleared on returning to userspace, due to performance reasons, which disabled the implicit STIBP and left userspace threads vulnerable to cross-thread branch target injection against which STIBP protects.
How to fix
This vulnerability affects an unusually large number of packages. The highest-confidence fixes are shown above; the full list is longer. Check the referenced advisories for complete coverage.
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Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N
Exploit Intelligence
Elevated risk: more likely to be exploited than 71% of all known CVEs.
References
Related Vulnerabilities
Other CWE-1303 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2026-59130 | High | 5.6 | 0.3% | - | Fix |
| CVE-2026-59131 | High | 5.6 | 0.3% | - | Fix |
| CVE-2023-38575 | Medium | 5.5 | 0.3% | - | Fix |
| CVE-2023-40540 | Medium | 4.1 | 0.2% | - | - |
Common questions
How do I fix CVE-2023-1998?
Published advisories record a fix for 330 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2023-1998 being actively exploited?
Not that we know of. CVE-2023-1998 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 1.4% is the estimated probability that it will be exploited in the next 30 days. That is higher than 71% of all scored CVEs.
How severe is CVE-2023-1998?
CVE-2023-1998 has a CVSS v3 base score of 5.6, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2023-1998 affect?
Published advisories record a fix for bpftool (Amazon), bpftool-debuginfo (Amazon), kernel (Amazon), kernel-debuginfo (Amazon), and 326 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-17.