How severe is CVE-2021-3593?

CVE-2021-3593 has a CVSS 3.x base score of 3.8, rated low severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2021-3593 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-2021-3593?

CVE-2021-3593 primarily affects Redhat Enterprise Linux. In total, 6 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-3593?

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

When was CVE-2021-3593 published?

CVE-2021-3593 was published on 2021-06-15 and last updated on 2026-06-17.

CVE-2021-3593

CVE-2021-3593 is a low-severity vulnerability in Redhat Enterprise Linux with a CVSS 3.x base score of 3.8. 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-824.

Key facts

Severity: Low (CVSS 3.x base score 3.8)
CVSS v2: 2.1
EPSS exploit prediction: 0% (25th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-824
Affected product: Redhat Enterprise Linux
Published: 2021-06-15
Last modified: 2026-06-17

Description

An invalid pointer initialization issue was found in the SLiRP networking implementation of QEMU. The flaw exists in the udp6_input() function and could occur while processing a udp packet that is smaller than the size of the 'udphdr' structure. This issue may lead to out-of-bounds read access or indirect host memory disclosure to the guest. The highest threat from this vulnerability is to data confidentiality. This flaw affects libslirp versions prior to 4.6.0.

Frequently asked questions

What is CVE-2021-3593?: An invalid pointer initialization issue was found in the SLiRP networking implementation of QEMU. The flaw exists in the udp6_input() function and could occur while processing a udp packet that is smaller than the size of the 'udphdr' structure. This issue may lead to out-of-bounds read access or indirect host memory disclosure to the guest. The highest threat from this vulnerability is to data confidentiality. This flaw affects libslirp versions prior to 4.6.0.
How severe is CVE-2021-3593?: CVE-2021-3593 has a CVSS 3.x base score of 3.8, rated low severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2021-3593 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-2021-3593?: CVE-2021-3593 primarily affects Redhat Enterprise Linux. In total, 6 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-3593?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-3593 published?: CVE-2021-3593 was published on 2021-06-15 and last updated on 2026-06-17.

References

Affected products (6)

cpe:2.3:a:libslirp_project:libslirp:*:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:advanced_virtualization:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

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