How severe is CVE-2020-1983?

CVE-2020-1983 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2020-1983 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (81st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-1983?

CVE-2020-1983 primarily affects Libslirp Project Libslirp. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-1983?

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-2020-1983 published?

CVE-2020-1983 was published on 2020-04-22 and last updated on 2026-06-17.

CVE-2020-1983

CVE-2020-1983 is a high-severity vulnerability in Libslirp Project Libslirp with a CVSS 3.x base score of 7.5. 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-416.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 2.1
EPSS exploit prediction: 2% (81st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-416
Affected product: Libslirp Project Libslirp
Published: 2020-04-22
Last modified: 2026-06-17

Description

A use after free vulnerability in ip_reass() in ip_input.c of libslirp 4.2.0 and prior releases allows crafted packets to cause a denial of service.

Frequently asked questions

What is CVE-2020-1983?: A use after free vulnerability in ip_reass() in ip_input.c of libslirp 4.2.0 and prior releases allows crafted packets to cause a denial of service.
How severe is CVE-2020-1983?: CVE-2020-1983 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2020-1983 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (81st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-1983?: CVE-2020-1983 primarily affects Libslirp Project Libslirp. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-1983?: 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-2020-1983 published?: CVE-2020-1983 was published on 2020-04-22 and last updated on 2026-06-17.

References

Affected products (10)

cpe:2.3:a:libslirp_project:libslirp:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:19.10:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:20.04:*:*:*:lts:*:*:*

More vulnerabilities in Libslirp Project Libslirp

CVE-2019-14378 — High (CVSS 8.8): ip_reass in ip_input.c in libslirp 4.0.0 has a heap-based buffer overflow via a large packet because it mishandles a…
CVE-2020-7211 — High (CVSS 7.5): tftp.c in libslirp 4.1.0, as used in QEMU 4.2.0, does not prevent ..\ directory traversal on Windows.
CVE-2019-15890 — High (CVSS 7.5): libslirp 4.0.0, as used in QEMU 4.1.0, has a use-after-free in ip_reass in ip_input.c.
CVE-2020-10756 — Medium (CVSS 6.5): An out-of-bounds read vulnerability was found in the SLiRP networking implementation of the QEMU emulator. This flaw…
CVE-2020-8608 — Medium (CVSS 5.6): In libslirp 4.1.0, as used in QEMU 4.2.0, tcp_subr.c misuses snprintf return values, leading to a buffer overflow in…
CVE-2020-7039 — Medium (CVSS 5.6): tcp_emu in tcp_subr.c in libslirp 4.1.0, as used in QEMU 4.2.0, mismanages memory, as demonstrated by IRC DCC commands…

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Other CWE-416 (Use After Free) vulnerabilities

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CVE-2026-4725 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 149…
CVE-2026-4688 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability was fixed in Firefox…
CVE-2025-24085 — Critical (CVSS 10.0): A use after free issue was addressed with improved memory management. This issue is fixed in iOS 18.3 and iPadOS 18.3,…
CVE-2024-43102 — Critical (CVSS 10.0): Concurrent removals of certain anonymous shared memory mappings by using the UMTX_SHM_DESTROY sub-request of…
CVE-2021-32495 — Critical (CVSS 10.0): Radare2 has a use-after-free vulnerability in pyc parser's get_none_object function. Attacker can read freed memory…

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