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CVE-2026-120830

Libslirp: libslirp: out-of-bounds heap read in icmp_forward_error() leading to information disclosure

7.4 High

A flaw was found in libslirp in icmp_forward_error(). When building an ICMP error response, the length of the quoted original IPv4 packet was taken from the IP header without clamping it to the actual buffer length. A truncated or malformed packet could cause an out-of-bounds heap read, leaking host memory into the ICMP error packet returned to a guest or container.

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
High
Integrity
None
Availability
None

Exploit likelihood

0.22%Unchanged since Nov 3, 2026
90%50%10%1%

What each source reports

CVE List Score used 7.4

Libslirp: libslirp: out-of-bounds heap read in icmp_forward_error() leading to information disclosure

A flaw was found in libslirp in icmp_forward_error(). When building an ICMP error response, the length of the quoted original IPv4 packet was taken from the IP header without clamping it to the actual buffer length. A truncated or malformed packet could cause an out-of-bounds heap read, leaking host memory into the ICMP error packet returned to a guest or container.

Record
CVE-2026-120830
CVSS 3.1
7.4 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Weakness
CWE-125
Updated
2026-11-04
EUVDEUVD-2026-115651 7.4

A flaw was found in libslirp in icmp_forward_error(). When building an ICMP error response, the length of the quoted original IPv4 packet was taken from the IP header without clamping it to the actual buffer length. A truncated or malformed packet could cause an out-of-bounds heap read, leaking host memory into the ICMP error packet returned to a guest or container.

Record
EUVD-2026-115651
CVSS 3.1
7.4 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Updated
2026-11-04
GitHub AdvisoriesGHSA-r5f9-pc8m-f599 7.4

A flaw was found in libslirp in icmp_forward_error(). When building an ICMP error response, the...

A flaw was found in libslirp in icmp_forward_error(). When building an ICMP error response, the length of the quoted original IPv4 packet was taken from the IP header without clamping it to the actual buffer length. A truncated or malformed packet could cause an out-of-bounds heap read, leaking host memory into the ICMP error packet returned to a guest or container.

Record
GHSA-r5f9-pc8m-f599
CVSS 3.1
7.4 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Weakness
CWE-125
Updated
2026-11-03
NVD 7.4

A flaw was found in libslirp in icmp_forward_error(). When building an ICMP error response, the length of the quoted original IPv4 packet was taken from the IP header without clamping it to the actual buffer length. A truncated or malformed packet could cause an out-of-bounds heap read, leaking host memory into the ICMP error packet returned to a guest or container.

Record
CVE-2026-120830
CVSS 3.1
7.4 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Weakness
CWE-125
Updated
2026-11-04
OSV 7.4

Libslirp: libslirp: out-of-bounds heap read in icmp_forward_error() leading to information disclosure

A flaw was found in libslirp in icmp_forward_error(). When building an ICMP error response, the length of the quoted original IPv4 packet was taken from the IP header without clamping it to the actual buffer length. A truncated or malformed packet could cause an out-of-bounds heap read, leaking host memory into the ICMP error packet returned to a guest or container.

Record
CVE-2026-120830
CVSS 3.1
7.4 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Weakness
CWE-125
Updated
2026-11-06
OSVDEBIAN-CVE-2026-120830 7.4

A flaw was found in libslirp in icmp_forward_error(). When building an ICMP error response, the length of the quoted original IPv4 packet was taken from the IP header without clamping it to the actual buffer length. A truncated or malformed packet could cause an out-of-bounds heap read, leaking host memory into the ICMP error packet returned to a guest or container.

Record
DEBIAN-CVE-2026-120830
CVSS 3.1
7.4 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Updated
2026-11-05
OSVUBUNTU-CVE-2026-120830 7.4

A flaw was found in libslirp in icmp_forward_error(). When building an ICMP error response, the length of the quoted original IPv4 packet was taken from the IP header without clamping it to the actual buffer length. A truncated or malformed packet could cause an out-of-bounds heap read, leaking host memory into the ICMP error packet returned to a guest or container.

Record
UBUNTU-CVE-2026-120830
CVSS 3.1
7.4 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Updated
2026-11-05
OSVAZL-112679 No score

CVE-2026-120830 affecting package libslirp 4.9.6-1

A flaw was found in libslirp in icmp_forward_error(). When building an ICMP error response, the length of the quoted original IPv4 packet was taken from the IP header without clamping it to the actual buffer length. A truncated or malformed packet could cause an out-of-bounds heap read, leaking host memory into the ICMP error packet returned to a guest or container.

Record
AZL-112679
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, referencesCVE List, EUVD, NVD, OSV
affected, aliases, published, referencesOSV
factsOSV
affected, aliases, referencesOSV
referencesNVD, OSV
aliases, publishedEUVD
products, published, references, severity, titleCVE List
first indexedGitHub Advisories

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

In short

CVE-2026-120830 is a high vulnerability (CVSS 7.4) 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 0.22%, the 12th percentile. No source names a fixed version.

References

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