An invalid pointer initialization issue was found in the SLiRP networking implementation…
Priority LOW 18CWE-824Published · Updated
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- Low · None · None
- Fix status
- Partial Red Hat: 2 fixed, 7 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.
Summary
An invalid pointer initialization issue was found in the SLiRP networking implementation of QEMU. The flaw exists in the udp_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.
Why it matters now
EPSS 0.00326 25th percentileScored 2026-11-07
Fix Partial Red Hat: 1 advisoryRed Hat: 2 fixed, 7 without a fix
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | QEMU | libslirp 4.6.0 | — | No fix listed | CNA |
- QEMU Vendor— Affected libslirp 4.6.0 Fixed in — No fix listed CNA
CPE configurations NVD · 6
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:libslirp_project:libslirp:*:*:*:*:*:*:*:* | before 4.6.0 | Vulnerable | Libslirp Project |
| cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:* | 8.0 | Vulnerable | Red Hat |
| cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:advanced_virtualization:*:*:* | 8.0 | Vulnerable | Red Hat |
| cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* | 9.0 | Vulnerable | Debian |
| cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* | 33 | Vulnerable | Fedoraproject |
| cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* | 34 | Vulnerable | Fedoraproject |
- cpe:2.3:a:libslirp_project:libslirp:*:*:*:*:*:*:*:* Versions before 4.6.0 Vulnerable ·Libslirp Project
- cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:* Versions 8.0 Vulnerable ·Red Hat
- cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:advanced_virtualization:*:*:* Versions 8.0 Vulnerable ·Red Hat
- cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Debian
- cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* Versions 33 Vulnerable ·Fedoraproject
- cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* Versions 34 Vulnerable ·Fedoraproject
Remediation
Red Hat 1 advisory
- RHSA-2021:4191 Released 2021-11-09 · Red Hat rating Moderatevirt:rhel and virt-devel:rhel security, bug fix, and enhancement update
- Red Hat CodeReady Linux Builder (v. 8) SLOF-20191022-3.git899d9883.module+el8.3.0+6423+e4cb6418.src::virt-devel:rhel, hivex-1.3.18-21.module+el8.5.0+10709+b3edb581.i686::virt-devel:rhel, hivex-devel-1.3.18-21.module+el8.5.0+10709+b3edb581.i686::virt-devel:rhel +47
- Red Hat Enterprise Linux AppStream (v. 8) SLOF-20191022-3.git899d9883.module+el8.3.0+6423+e4cb6418.noarch::virt:rhel, SLOF-20191022-3.git899d9883.module+el8.3.0+6423+e4cb6418.src::virt:rhel, hivex-1.3.18-21.module+el8.5.0+10709+b3edb581.aarch64::virt:rhel +47
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Advisory ·
QEMU — FEDORA-2021-71de23bedd
4 records Highest priority Priority LOW 4 LOW
Other records, highest priority first
- TI-2021-02542 An invalid pointer initialization issue was found in the SLiRP networking implementation…Priority LOW 18
- TI-2021-02540 An invalid pointer initialization issue was found in the SLiRP networking implementation…Priority LOW 18
- TI-2021-02539 An invalid pointer initialization issue was found in the SLiRP networking implementation…Priority LOW 18
- Advisory ·
QEMU — FEDORA-2021-7cd749f133
4 records Highest priority Priority LOW 4 LOW
Other records, highest priority first
- TI-2021-02542 An invalid pointer initialization issue was found in the SLiRP networking implementation…Priority LOW 18
- TI-2021-02540 An invalid pointer initialization issue was found in the SLiRP networking implementation…Priority LOW 18
- TI-2021-02539 An invalid pointer initialization issue was found in the SLiRP networking implementation…Priority LOW 18
Show 1 more group
- Advisory ·
QEMU — GLSA-202107-44
4 records Highest priority Priority LOW 4 LOW
Other records, highest priority first
- TI-2021-02542 An invalid pointer initialization issue was found in the SLiRP networking implementation…Priority LOW 18
- TI-2021-02540 An invalid pointer initialization issue was found in the SLiRP networking implementation…Priority LOW 18
- TI-2021-02539 An invalid pointer initialization issue was found in the SLiRP networking implementation…Priority LOW 18
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 Advanced Virtualization | Affected | No fix yet |
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
| Red Hat OpenStack Platform 10 (Newton) | Affected | No fix planned: Out of support scope |
| Red Hat OpenStack Platform 13 (Queens) | Affected | No fix planned: Out of support scope |
| Red Hat CodeReady Linux Builder (v. 8) | Fixed | RHSA-2021:4191 |
| Red Hat Enterprise Linux AppStream (v. 8) | Fixed | RHSA-2021:4191 |
Not affected: 1 product
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2021-3594
- 2026-10-03 Alias added: GHSA-wh9f-45px-j437
References
Advisory 5
Sources
- CVE-2021-3594 · CVE Program
- CVE-2021-3594 · NVD
- FIRST EPSS
- GHSA-wh9f-45px-j437 · GitHub Advisory Database · CC BY 4.0
- CVE-2021-3594 · Red Hat security data · CC BY 4.0
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