How severe is CVE-2020-29040?

CVE-2020-29040 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-29040 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (29th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-29040?

CVE-2020-29040 affects Xen. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-29040?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2020-29040 published?

CVE-2020-29040 was published on 2020-11-24 and last updated on 2026-06-17.

CVE-2020-29040

CVE-2020-29040 is a high-severity vulnerability in Xen with a CVSS 3.x base score of 8.8. 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-193.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 4.6
EPSS exploit prediction: 0% (29th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-193
Affected product: Xen
Published: 2020-11-24
Last modified: 2026-06-17

Description

An issue was discovered in Xen through 4.14.x allowing x86 HVM guest OS users to cause a denial of service (stack corruption), cause a data leak, or possibly gain privileges because of an off-by-one error. NOTE: this issue is caused by an incorrect fix for CVE-2020-27671.

Frequently asked questions

What is CVE-2020-29040?: An issue was discovered in Xen through 4.14.x allowing x86 HVM guest OS users to cause a denial of service (stack corruption), cause a data leak, or possibly gain privileges because of an off-by-one error. NOTE: this issue is caused by an incorrect fix for CVE-2020-27671.
How severe is CVE-2020-29040?: CVE-2020-29040 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-29040 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (29th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-29040?: CVE-2020-29040 affects Xen. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-29040?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2020-29040 published?: CVE-2020-29040 was published on 2020-11-24 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:o:xen:xen:*:*:*:*:*:*:*:*

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Other CWE-193 (Off-by-one Error) vulnerabilities

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CVE-2023-46853 — Critical (CVSS 9.8): In Memcached before 1.6.22, an off-by-one error exists when processing proxy requests in proxy mode, if \n is used…
CVE-2023-38429 — Critical (CVSS 9.8): An issue was discovered in the Linux kernel before 6.3.4. fs/ksmbd/connection.c in ksmbd has an off-by-one error in…
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Browse all CWE-193 (Off-by-one Error) vulnerabilities →