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CVE-2020-29129· NVD / CVE Program· CNA mitre

ncsi.c in libslirp through 4.3.1 has a buffer over-read because it tries to read a certain amount of header data even if that exceeds the to

Noroxi assessment

Priority: Monitor (action score 17/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 1.4% (FIRST EPSS); higher than 73.4% of all records.
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: hivex (AlmaLinux:8) 1.3.18-20.module_el8.3.0+2048+e7a0a3ea; hivex-devel (AlmaLinux:8) 1.3.18-20.module_el8.3.0+2048+e7a0a3ea; libguestfs-winsupport (AlmaLinux:8) 8.2-1.module_el8.3.0+2048+e7a0a3ea, 8.2-1.module_el8.5.0+2608+72063365.

Low priority for now. Upgrade to hivex (AlmaLinux:8) 1.3.18-20.module_el8.3.0+2048+e7a0a3ea; hivex-devel (AlmaLinux:8) 1.3.18-20.module_el8.3.0+2048+e7a0a3ea; libguestfs-winsupport (AlmaLinux:8) 8.2-1.module_el8.3.0+2048+e7a0a3ea, 8.2-1.module_el8.5.0+2608+72063365 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

ncsi.c in libslirp through 4.3.1 has a buffer over-read because it tries to read a certain amount of header data even if that exceeds the total packet length.

MediumCVSS 4.3 · v3.1—No exploit Fix available
Published
Nov 26, 2020
Updated
Jun 16, 2026
EPSS
1.4% · 73th percentile

Report tools

JSON

Action score

17

Monitor

Low priority for now.

CVSS
17 / 40 · 4.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.4%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2020-29129

When you'll hear from us

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  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
libslirp projectlibslirp
fedoraprojectfedora
debiandebian linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • debian debian linux10.0
  • fedoraproject fedora32
  • fedoraproject fedora33
  • libslirp project libslirpup to 4.3.1 inclusive

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:8hivexbefore 1.3.18-20.module_el8.3.0+2048+e7a0a3ea1.3.18-20.module_el8.3.0+2048+e7a0a3ea
AlmaLinux:8hivex-develbefore 1.3.18-20.module_el8.3.0+2048+e7a0a3ea1.3.18-20.module_el8.3.0+2048+e7a0a3ea
AlmaLinux:8libguestfs-winsupportbefore 8.2-1.module_el8.3.0+2048+e7a0a3ea8.2-1.module_el8.3.0+2048+e7a0a3ea
AlmaLinux:8libguestfs-winsupportbefore 8.2-1.module_el8.5.0+2608+720633658.2-1.module_el8.5.0+2608+72063365
AlmaLinux:8libiscsibefore 1.18.0-8.module_el8.6.0+2880+7d9e37031.18.0-8.module_el8.6.0+2880+7d9e3703
AlmaLinux:8libiscsibefore 1.18.0-8.module_el8.5.0+2608+720633651.18.0-8.module_el8.5.0+2608+72063365
AlmaLinux:8libiscsibefore 1.18.0-8.module_el8.3.0+2048+e7a0a3ea1.18.0-8.module_el8.3.0+2048+e7a0a3ea
AlmaLinux:8libiscsi-develbefore 1.18.0-8.module_el8.3.0+2048+e7a0a3ea1.18.0-8.module_el8.3.0+2048+e7a0a3ea
AlmaLinux:8libiscsi-develbefore 1.18.0-8.module_el8.5.0+2608+720633651.18.0-8.module_el8.5.0+2608+72063365
AlmaLinux:8libiscsi-develbefore 1.18.0-8.module_el8.6.0+2880+7d9e37031.18.0-8.module_el8.6.0+2880+7d9e3703
AlmaLinux:8libiscsi-utilsbefore 1.18.0-8.module_el8.5.0+2608+720633651.18.0-8.module_el8.5.0+2608+72063365
AlmaLinux:8libiscsi-utilsbefore 1.18.0-8.module_el8.3.0+2048+e7a0a3ea1.18.0-8.module_el8.3.0+2048+e7a0a3ea
AlmaLinux:8libiscsi-utilsbefore 1.18.0-8.module_el8.6.0+2880+7d9e37031.18.0-8.module_el8.6.0+2880+7d9e3703
AlmaLinux:8libnbdbefore 1.2.2-1.module_el8.5.0+2608+720633651.2.2-1.module_el8.5.0+2608+72063365
AlmaLinux:8libnbdbefore 1.2.2-1.module_el8.3.0+2048+e7a0a3ea1.2.2-1.module_el8.3.0+2048+e7a0a3ea
AlmaLinux:8libnbd-develbefore 1.2.2-1.module_el8.3.0+2048+e7a0a3ea1.2.2-1.module_el8.3.0+2048+e7a0a3ea
AlmaLinux:8libnbd-develbefore 1.2.2-1.module_el8.5.0+2608+720633651.2.2-1.module_el8.5.0+2608+72063365
AlmaLinux:8libvirt-dbusbefore 1.3.0-2.module_el8.5.0+2608+720633651.3.0-2.module_el8.5.0+2608+72063365
AlmaLinux:8libvirt-dbusbefore 1.3.0-2.module_el8.6.0+2880+7d9e37031.3.0-2.module_el8.6.0+2880+7d9e3703
AlmaLinux:8libvirt-dbusbefore 1.3.0-2.module_el8.3.0+2048+e7a0a3ea1.3.0-2.module_el8.3.0+2048+e7a0a3ea
AlmaLinux:8nbdfusebefore 1.2.2-1.module_el8.3.0+2048+e7a0a3ea1.2.2-1.module_el8.3.0+2048+e7a0a3ea
AlmaLinux:8nbdfusebefore 1.2.2-1.module_el8.5.0+2608+720633651.2.2-1.module_el8.5.0+2608+72063365
AlmaLinux:8nbdkitbefore 1.16.2-4.module_el8.5.0+2608+720633651.16.2-4.module_el8.5.0+2608+72063365
AlmaLinux:8nbdkit-bash-completionbefore 1.16.2-4.module_el8.5.0+2608+720633651.16.2-4.module_el8.5.0+2608+72063365

+96

Same product

libslirp project: all records

Other highest-scoring records for the same primary product.

  • CVE-2019-14378ip_reass in ip_input.c in libslirp 4.0.0 has a heap-based buffer overflow via a large packet because it mishandles a case involving the firs
    40Plan
  • CVE-2020-1983libslirp: use after free vulnerability cause a denial of service.
    27Monitor
  • CVE-2020-10756An out-of-bounds read vulnerability was found in the SLiRP networking implementation of the QEMU emulator.
    26Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2020-8608Feb 6, 2020 · 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 later code.
    23Monitor
  • Later →CVE-2020-29130Nov 26, 2020 · slirp.c in libslirp through 4.3.1 has a buffer over-read because it tries to read a certain amount of header data even if that exceeds the t
    18Monitor
  • Later →CVE-2021-3592Jun 15, 2021 · An invalid pointer initialization issue was found in the SLiRP networking implementation of QEMU.
    15Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
almalinux:hivex1.3.18-20.module_el8.3.0+2048+e7a0a3ea · AlmaLinux:8Package registry (OSV)
almalinux:hivex-devel1.3.18-20.module_el8.3.0+2048+e7a0a3ea · AlmaLinux:8Package registry (OSV)
almalinux:libguestfs-winsupport8.2-1.module_el8.5.0+2608+72063365 · AlmaLinux:8Package registry (OSV)
almalinux:libiscsi1.18.0-8.module_el8.6.0+2880+7d9e3703 · AlmaLinux:8Package registry (OSV)
almalinux:libiscsi-devel1.18.0-8.module_el8.6.0+2880+7d9e3703 · AlmaLinux:8Package registry (OSV)
almalinux:libiscsi-utils1.18.0-8.module_el8.3.0+2048+e7a0a3ea · AlmaLinux:8Package registry (OSV)
almalinux:libnbd1.2.2-1.module_el8.5.0+2608+72063365 · AlmaLinux:8Package registry (OSV)
almalinux:libnbd-devel1.2.2-1.module_el8.3.0+2048+e7a0a3ea · AlmaLinux:8Package registry (OSV)
almalinux:libvirt-dbus1.3.0-2.module_el8.6.0+2880+7d9e3703 · AlmaLinux:8Package registry (OSV)
almalinux:nbdfuse1.2.2-1.module_el8.3.0+2048+e7a0a3ea · AlmaLinux:8Package registry (OSV)
almalinux:nbdkit1.16.2-4.module_el8.5.0+2608+72063365 · AlmaLinux:8Package registry (OSV)
almalinux:nbdkit-bash-completion1.16.2-4.module_el8.5.0+2608+72063365 · AlmaLinux:8Package registry (OSV)
debian:libslirp4.4.0-1 · Debian:12Package registry (OSV)
debian:qemu1:4.1-2 · Debian:12Package registry (OSV)
opensuse:qemu4.2.1-lp152.9.12.1 · openSUSE:Leap 15.2Package registry (OSV)
opensuse:qemu-linux-user4.2.1-lp152.9.12.1 · openSUSE:Leap 15.2Package registry (OSV)
opensuse:qemu-testsuite4.2.1-lp152.9.12.1 · openSUSE:Leap 15.2Package registry (OSV)
opensuse:slirp4netns0.4.7-150100.3.18.1 · openSUSE:Leap Micro 5.3Package registry (OSV)
red hat:hivex0:1.3.18-20.module+el8.3.0+6423+e4cb6418 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:hivex-debuginfo0:1.3.18-20.module+el8.3.0+6423+e4cb6418 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:hivex-debugsource0:1.3.18-20.module+el8.3.0+6423+e4cb6418 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:hivex-devel0:1.3.18-20.module+el8.3.0+6423+e4cb6418 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:libguestfs1:1.40.2-27.module+el8.4.0+9282+0bdec052 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:libguestfs-bash-completion1:1.40.2-27.module+el8.4.0+9282+0bdec052 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:libguestfs-benchmarking1:1.40.2-27.module+el8.4.0+9282+0bdec052 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:libguestfs-benchmarking-debuginfo1:1.40.2-27.module+el8.4.0+9282+0bdec052 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:libguestfs-debuginfo1:1.40.2-27.module+el8.4.0+9282+0bdec052 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:libguestfs-debugsource1:1.40.2-27.module+el8.4.0+9282+0bdec052 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:libguestfs-devel1:1.40.2-27.module+el8.4.0+9282+0bdec052 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:SLOF0:20191022-3.git899d9883.module+el8.3.0+6423+e4cb6418 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)

+14

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
low · data can be read
Integrity
none
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
Low
Integrity impact
None
Availability impact
None

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (4 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records