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CVE-2026-120831

Libslirp: libslirp: queue pointer corruption in if_output() leading to denial of service

6.5 Medium

A flaw was found in libslirp in if_output(). When moving a session from the fast queue to the batch queue, the code unlinked and reinserted an arbitrary packet via ifm->m_nextpkt instead of the session queue head, corrupting queue pointers. A guest generating burst traffic could crash the host networking process, causing a denial of service.

Attack profile

How easy it is to exploit

Attack vector
Adjacent network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.27%Unchanged since Nov 3, 2026
90%50%10%1%

What each source reports

CVE List Score used 6.5

Libslirp: libslirp: queue pointer corruption in if_output() leading to denial of service

A flaw was found in libslirp in if_output(). When moving a session from the fast queue to the batch queue, the code unlinked and reinserted an arbitrary packet via ifm->m_nextpkt instead of the session queue head, corrupting queue pointers. A guest generating burst traffic could crash the host networking process, causing a denial of service.

Record
CVE-2026-120831
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-787
Updated
2026-11-05
EUVDEUVD-2026-115656 6.5

A flaw was found in libslirp in if_output(). When moving a session from the fast queue to the batch queue, the code unlinked and reinserted an arbitrary packet via ifm->m_nextpkt instead of the session queue head, corrupting queue pointers. A guest generating burst traffic could crash the host networking process, causing a denial of service.

Record
EUVD-2026-115656
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-05
GitHub AdvisoriesGHSA-c4qr-qpmh-whrf 6.5

A flaw was found in libslirp in if_output(). When moving a session from the fast queue to the...

A flaw was found in libslirp in if_output(). When moving a session from the fast queue to the batch queue, the code unlinked and reinserted an arbitrary packet via ifm->m_nextpkt instead of the session queue head, corrupting queue pointers. A guest generating burst traffic could crash the host networking process, causing a denial of service.

Record
GHSA-c4qr-qpmh-whrf
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-787
Updated
2026-11-03
NVD 6.5

A flaw was found in libslirp in if_output(). When moving a session from the fast queue to the batch queue, the code unlinked and reinserted an arbitrary packet via ifm->m_nextpkt instead of the session queue head, corrupting queue pointers. A guest generating burst traffic could crash the host networking process, causing a denial of service.

Record
CVE-2026-120831
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-787
Updated
2026-11-05
OSV 6.5

Libslirp: libslirp: queue pointer corruption in if_output() leading to denial of service

A flaw was found in libslirp in if_output(). When moving a session from the fast queue to the batch queue, the code unlinked and reinserted an arbitrary packet via ifm->m_nextpkt instead of the session queue head, corrupting queue pointers. A guest generating burst traffic could crash the host networking process, causing a denial of service.

Record
CVE-2026-120831
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-787
Updated
2026-11-07
OSVDEBIAN-CVE-2026-120831 6.5

A flaw was found in libslirp in if_output(). When moving a session from the fast queue to the batch queue, the code unlinked and reinserted an arbitrary packet via ifm->m_nextpkt instead of the session queue head, corrupting queue pointers. A guest generating burst traffic could crash the host networking process, causing a denial of service.

Record
DEBIAN-CVE-2026-120831
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-04
OSVUBUNTU-CVE-2026-120831 6.5

A flaw was found in libslirp in if_output(). When moving a session from the fast queue to the batch queue, the code unlinked and reinserted an arbitrary packet via ifm->m_nextpkt instead of the session queue head, corrupting queue pointers. A guest generating burst traffic could crash the host networking process, causing a denial of service.

Record
UBUNTU-CVE-2026-120831
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-05
OSVAZL-112682 No score

CVE-2026-120831 affecting package libslirp 4.9.6-1

A flaw was found in libslirp in if_output(). When moving a session from the fast queue to the batch queue, the code unlinked and reinserted an arbitrary packet via ifm->m_nextpkt instead of the session queue head, corrupting queue pointers. A guest generating burst traffic could crash the host networking process, causing a denial of service.

Record
AZL-112682
Updated
2026-11-05

Affected products

Affected packages

Affected packages
PackageAffectedFixed
libslirp
Azure Linux:3
through 4.9.6-1 None known
libslirp
Debian:12
All versions, plus listed versions
4.7.0-14.8.0-14.9.1-14.9.2-14.9.3-14.9.4-14.9.5-1
None known
libslirp
Debian:13
All versions, plus listed versions
4.8.0-14.8.0-1+deb13u14.9.1-14.9.2-14.9.3-14.9.4-14.9.5-1
None known
libslirp
Debian:14
All versions, plus listed versions
4.8.0-14.9.1-14.9.2-14.9.3-14.9.4-14.9.5-1
None known
libslirp
Ubuntu:20.04:LTS
All versions, plus listed versions
4.0.0-14.0.0-24.1.0-14.1.0-24.1.0-2ubuntu14.1.0-2ubuntu24.1.0-2ubuntu2.14.1.0-2ubuntu2.2
None known
libslirp
Ubuntu:22.04:LTS
All versions, plus listed versions
4.4.0-1build14.6.1-14.6.1-1build14.6.1-1ubuntu0.2
None known
libslirp
Ubuntu:24.04:LTS
All versions, plus listed versions
4.7.0-1ubuntu14.7.0-1ubuntu24.7.0-1ubuntu34.7.0-1ubuntu3.1
None known
libslirp
Ubuntu:26.10
All versions, plus listed versions
4.9.1-1ubuntu14.9.3-1ubuntu1
None known
libslirp
Ubuntu:26.04:LTS
All versions, plus listed versions
4.8.0-1ubuntu14.9.1-1ubuntu14.9.1-1ubuntu1.1
None known

History

History
RecordedChangedSources
affected, aliases, published, referencesOSV
affected, aliases, published, referencesNVD, OSV
factsCVE List, EUVD
affected, aliases, referencesOSV
referencesOSV
publishedEUVD, NVD
aliasesEUVD
aliases, referencesGitHub Advisories
first indexedCVE List

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-120831 is a medium vulnerability (CVSS 6.5) in Red Hat Enterprise Linux 10, published November 3, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.27%, the 18th percentile. No source names a fixed version.

References

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