How severe is CVE-2021-26313?

CVE-2021-26313 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2021-26313 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (25th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-26313?

CVE-2021-26313 primarily affects Xen. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-26313?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-26313 published?

CVE-2021-26313 was published on 2021-06-09 and last updated on 2026-06-17.

CVE-2021-26313

CVE-2021-26313 is a medium-severity vulnerability in Xen with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-203.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
CVSS v2: 2.1
EPSS exploit prediction: 0% (25th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-203
Affected product: Xen
Published: 2021-06-09
Last modified: 2026-06-17

Description

Potential speculative code store bypass in all supported CPU products, in conjunction with software vulnerabilities relating to speculative execution of overwritten instructions, may cause an incorrect speculation and could result in data leakage.

Frequently asked questions

What is CVE-2021-26313?: Potential speculative code store bypass in all supported CPU products, in conjunction with software vulnerabilities relating to speculative execution of overwritten instructions, may cause an incorrect speculation and could result in data leakage.
How severe is CVE-2021-26313?: CVE-2021-26313 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2021-26313 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (25th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-26313?: CVE-2021-26313 primarily affects Xen. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-26313?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-26313 published?: CVE-2021-26313 was published on 2021-06-09 and last updated on 2026-06-17.

References

https://www.amd.com/en/corporate/product-security/bulletin/amd-sb-1003

Affected products (8)

cpe:2.3:o:xen:xen:*:*:*:*:*:*:*:*
cpe:2.3:h:arm:cortex-a72:-:*:*:*:*:*:*:*
cpe:2.3:h:broadcom:bcm2711:-:*:*:*:*:*:*:*
cpe:2.3:h:intel:core_i7-10700k:-:*:*:*:*:*:*:*
cpe:2.3:h:intel:core_i7-7700k:-:*:*:*:*:*:*:*
cpe:2.3:h:intel:core_i9-9900k:-:*:*:*:*:*:*:*
cpe:2.3:h:intel:xeon_silver_4214:-:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

More vulnerabilities in Xen

CVE-2017-10921 — Critical (CVSS 10.0): The grant-table feature in Xen through 4.8.x does not ensure sufficient type counts for a GNTMAP_device_map and…
CVE-2017-10920 — Critical (CVSS 10.0): The grant-table feature in Xen through 4.8.x mishandles a GNTMAP_device_map and GNTMAP_host_map mapping, when followed…
CVE-2017-10918 — Critical (CVSS 10.0): Xen through 4.8.x does not validate memory allocations during certain P2M operations, which allows guest OS users to…
CVE-2017-10912 — Critical (CVSS 10.0): Xen through 4.8.x mishandles page transfer, which allows guest OS users to obtain privileged host OS access, aka…
CVE-2015-8104 — Critical (CVSS 10.0): The KVM subsystem in the Linux kernel through 4.2.6, and Xen 4.3.x through 4.6.x, allows guest OS users to cause a…
CVE-2018-12892 — Critical (CVSS 9.9): An issue was discovered in Xen 4.7 through 4.10.x. libxl fails to pass the readonly flag to qemu when setting up a SCSI…

All CVEs affecting Xen →

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CVE-2024-25714 — Critical (CVSS 9.8): In Rhonabwy through 1.1.13, HMAC signature verification uses a strcmp function that is vulnerable to side-channel…
CVE-2024-25191 — Critical (CVSS 9.8): php-jwt 1.0.0 uses strcmp (which is not constant time) to verify authentication, which makes it easier to bypass…
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Browse all CWE-203 (Observable Discrepancy) vulnerabilities →