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CVE-2026-41326

Kata Containers: CopyFile Policy Subversion via Symlinks

8.2 HighFix available

Kata Containers is an open source project focusing on a standard implementation of lightweight Virtual Machines (VMs) that perform like containers. From v3.4.0 to v3.28.0, an oversight in the CopyFile policy (and perhaps the CopyFile handler) allows untrusted hosts to write to arbitrary locations inside the guest workload image. This can be used to overwrite binaries inside the guest and exfiltrate data from containers; even those running inside CVMs. This vulnerability is fixed in v3.29.0.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
High
Availability
None

Exploit likelihood

0.35%Up 0.3 points since Apr 25, 2026
90%50%10%1%

What each source reports

CVE List Score used 8.2

Kata Containers: CopyFile Policy Subversion via Symlinks

Kata Containers is an open source project focusing on a standard implementation of lightweight Virtual Machines (VMs) that perform like containers. From v3.4.0 to v3.28.0, an oversight in the CopyFile policy (and perhaps the CopyFile handler) allows untrusted hosts to write to arbitrary locations inside the guest workload image. This can be used to overwrite binaries inside the guest and exfiltrate data from containers; even those running inside CVMs. This vulnerability is fixed in v3.29.0.

Record
CVE-2026-41326
CVSS 4.0
8.2 HighCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:H/SI:N/SA:N
CVSS 3.1
8.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Weakness
CWE-61, CWE-1220
Updated
2026-11-02
EUVDEUVD-2026-25611 8.2

Kata Containers is an open source project focusing on a standard implementation of lightweight Virtual Machines (VMs) that perform like containers. From v3.4.0 to v3.28.0, an oversight in the CopyFile policy (and perhaps the CopyFile handler) allows untrusted hosts to write to arbitrary locations inside the guest workload image. This can be used to overwrite binaries inside the guest and exfiltrate data from containers; even those running inside CVMs. This vulnerability is fixed in v3.29.0.

Record
EUVD-2026-25611
CVSS 4.0
8.2 HighCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:H/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-q49m-57vm-c8cc 8.2

Kata Container has CopyFile Policy Subversion via Symlinks

Summary

An oversight in the CopyFile policy (and perhaps the CopyFile handler) allows untrusted hosts to write to arbitrary locations inside the guest workload image. This can be used to overwrite binaries inside the guest and exfiltrate data from containers; even those running inside CVMs.

Details

Here is the policy that covers CopyFile requests.

CopyFileRequest if {
    print("CopyFileRequest: input.path =", input.path)
        
    check_directory_traversal(input.path)
        
    some regex1 in policy_data.request_defaults.CopyFileRequest
    regex2 := replace(regex1, "$(sfprefix)", policy_data.common.sfprefix)
    regex3 := replace(regex2, "$(cpath)", policy_data.common.cpath)
    regex4 := replace(regex3, "$(bundle-id)", "[a-z0-9]{64}")
    print("CopyFileRequest: regex4 =", regex4)
    
    regex.match(regex4, input.path)
      
    print("CopyFileRequest: true")
}

This checks that files are being copied to policy_data.common.cpath, which is typically set to /run/kata-containers/shared/containers. In other words, you're allowed to copy files to anywhere inside the shared dir.

For reference, here is the CopyFile message. Note that none of the other fields are check in the policy.

message CopyFileRequest {
	// Path is the destination file in the guest. It must be absolute,
	// canonical and below /run.
	string path = 1;
	// FileSize is the expected file size, for security reasons write operations
	// are made in a temporary file, once it has the expected size, it's moved
	// to the destination path.
	int64 file_size = 2;
	// FileMode is the file mode.
	uint32 file_mode = 3;
	// DirMode is the mode for the parent directories of destination path.
	uint32 dir_mode = 4;
	// Uid is the numeric user id.
	int32 uid = 5;
	// Gid is the numeric group id.
	int32 gid = 6;
	// Offset for the next write operation.
	int64 offset = 7;
	// Data to write in the destination file.
	bytes data = 8;
}

In addition to copying files directly, the Kata Agent supports creating symlinks via the CopyFile API. In this case the path is the symlink name and the data field contains the symlink target. Given that the policy only checks the path, an attacker can craft a CopyFile request that results in a symlink going from any location into the shared dir.

PoC

The above primitive can be used to to write arbitrary data into container images (pulled in the guest or otherwise). A couple steps are required.

First, identify some target path in the guest image. This could be a binary that will be called by the workload. You could also experiment with overwriting other stuff.

Create a symlink from this binary to the shared dir. The path/link name should be in the shared dir and the data/target should point to the path of the target file inside the container image in the guest fs.

Create a second CopyFile request to copy your data from the host into the symlink you just created in the shared dir. This will then be propagated into the image. You may want to restart the container to ensure that your new binary is invoked.

Impact

Anyone who is using the upstream genpolicy implementation and expects it to prevent host access to container images is vulnerable This includes Confidential Containers workloads where the trust model explicitly forbids this type of access. If you have your own policy implementation you may or may not be vulnerable. If you do not care about protecting the image from the host (e.g. you are using unprotected host pull), you are not vulnerable.

This was individually discovered and reported by

  • @calonso-nv
  • @fikriwahab
  • @kodareef5
Record
GHSA-q49m-57vm-c8cc
CVSS 4.0
8.2 HighCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:H/SI:N/SA:N
CVSS 3.1
8.2 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
Weakness
CWE-61
Updated
2026-11-02
NVD 8.2

Kata Containers is an open source project focusing on a standard implementation of lightweight Virtual Machines (VMs) that perform like containers. From v3.4.0 to v3.28.0, an oversight in the CopyFile policy (and perhaps the CopyFile handler) allows untrusted hosts to write to arbitrary locations inside the guest workload image. This can be used to overwrite binaries inside the guest and exfiltrate data from containers; even those running inside CVMs. This vulnerability is fixed in v3.29.0.

Record
CVE-2026-41326
CVSS 4.0
8.2 HighCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
8.2 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
CVSS 3.1
8.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Weakness
CWE-61, CWE-1220
Updated
2026-11-02
OSV 8.2

Kata Containers: CopyFile Policy Subversion via Symlinks

Kata Containers is an open source project focusing on a standard implementation of lightweight Virtual Machines (VMs) that perform like containers. From v3.4.0 to v3.28.0, an oversight in the CopyFile policy (and perhaps the CopyFile handler) allows untrusted hosts to write to arbitrary locations inside the guest workload image. This can be used to overwrite binaries inside the guest and exfiltrate data from containers; even those running inside CVMs. This vulnerability is fixed in v3.29.0.

Record
CVE-2026-41326
CVSS 4.0
8.2 HighCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:H/SI:N/SA:N
Weakness
CWE-61
Updated
2026-11-02
OSVGHSA-q49m-57vm-c8cc 8.2

Kata Container has CopyFile Policy Subversion via Symlinks

Summary

An oversight in the CopyFile policy (and perhaps the CopyFile handler) allows untrusted hosts to write to arbitrary locations inside the guest workload image. This can be used to overwrite binaries inside the guest and exfiltrate data from containers; even those running inside CVMs.

Details

Here is the policy that covers CopyFile requests.

CopyFileRequest if {
    print("CopyFileRequest: input.path =", input.path)
        
    check_directory_traversal(input.path)
        
    some regex1 in policy_data.request_defaults.CopyFileRequest
    regex2 := replace(regex1, "$(sfprefix)", policy_data.common.sfprefix)
    regex3 := replace(regex2, "$(cpath)", policy_data.common.cpath)
    regex4 := replace(regex3, "$(bundle-id)", "[a-z0-9]{64}")
    print("CopyFileRequest: regex4 =", regex4)
    
    regex.match(regex4, input.path)
      
    print("CopyFileRequest: true")
}

This checks that files are being copied to policy_data.common.cpath, which is typically set to /run/kata-containers/shared/containers. In other words, you're allowed to copy files to anywhere inside the shared dir.

For reference, here is the CopyFile message. Note that none of the other fields are check in the policy.

message CopyFileRequest {
	// Path is the destination file in the guest. It must be absolute,
	// canonical and below /run.
	string path = 1;
	// FileSize is the expected file size, for security reasons write operations
	// are made in a temporary file, once it has the expected size, it's moved
	// to the destination path.
	int64 file_size = 2;
	// FileMode is the file mode.
	uint32 file_mode = 3;
	// DirMode is the mode for the parent directories of destination path.
	uint32 dir_mode = 4;
	// Uid is the numeric user id.
	int32 uid = 5;
	// Gid is the numeric group id.
	int32 gid = 6;
	// Offset for the next write operation.
	int64 offset = 7;
	// Data to write in the destination file.
	bytes data = 8;
}

In addition to copying files directly, the Kata Agent supports creating symlinks via the CopyFile API. In this case the path is the symlink name and the data field contains the symlink target. Given that the policy only checks the path, an attacker can craft a CopyFile request that results in a symlink going from any location into the shared dir.

PoC

The above primitive can be used to to write arbitrary data into container images (pulled in the guest or otherwise). A couple steps are required.

First, identify some target path in the guest image. This could be a binary that will be called by the workload. You could also experiment with overwriting other stuff.

Create a symlink from this binary to the shared dir. The path/link name should be in the shared dir and the data/target should point to the path of the target file inside the container image in the guest fs.

Create a second CopyFile request to copy your data from the host into the symlink you just created in the shared dir. This will then be propagated into the image. You may want to restart the container to ensure that your new binary is invoked.

Impact

Anyone who is using the upstream genpolicy implementation and expects it to prevent host access to container images is vulnerable This includes Confidential Containers workloads where the trust model explicitly forbids this type of access. If you have your own policy implementation you may or may not be vulnerable. If you do not care about protecting the image from the host (e.g. you are using unprotected host pull), you are not vulnerable.

This was individually discovered and reported by

  • @calonso-nv
  • @fikriwahab
  • @kodareef5
Record
GHSA-q49m-57vm-c8cc
CVSS 4.0
8.2 HighCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:H/SI:N/SA:N
CVSS 3.1
8.2 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
Weakness
CWE-61
Updated
2026-11-02
OSVGO-2026-5563 No score

Kata Container has CopyFile Policy Subversion via Symlinks in github.com/kata-containers/kata-containers

Kata Container has CopyFile Policy Subversion via Symlinks in github.com/kata-containers/kata-containers

Record
GO-2026-5563
Updated
2026-11-02
OSVopenSUSE-SU-2026:21483-1 No score

Security update for govulncheck-vulndb

This update for govulncheck-vulndb fixes the following issues:

  • Update to version 0.0.20260723T184607 2026-07-23T18:46:07Z (jsc#PED-11136).

Go CVE Numbering Authority IDs added or updated with aliases:

  • GO-2026-4730 CVE-2026-33022 GHSA-cv4x-93xx-wgfj
  • GO-2026-4761 CVE-2026-33211 GHSA-j5q5-j9gm-2w5c
  • GO-2026-5102 CVE-2026-45021 GHSA-3vcp-chfh-f6r2
  • GO-2026-5272 CVE-2026-40938 GHSA-94jr-7pqp-xhcq
  • GO-2026-5486 CVE-2026-40924 GHSA-m2cx-gpqf-qf74
  • GO-2026-5542 CVE-2026-40090 GHSA-pj97-4p9w-gx3q
  • GO-2026-5630 CVE-2026-25542 GHSA-rmx9-2pp3-xhcr
  • GO-2026-5643 CVE-2026-40923 GHSA-rx35-6rhx-7858
  • GO-2026-5675 CVE-2026-41492 GHSA-vvf7-6rmr-m29q
  • GO-2026-5711 CVE-2026-40161 GHSA-wjxp-xrpv-xpff
  • GO-2026-5746 CVE-2026-41567 GHSA-x86f-5xw2-fm2r
  • GO-2026-5749 CVE-2026-41328 GHSA-x92x-px7w-4gx4
  • GO-2026-5837 CVE-2026-44840 GHSA-q2m9-6jp9-c6mc
  • GO-2026-5929 CVE-2026-44342 GHSA-26v7-h57m-gh9m
  • GO-2026-5930 CVE-2026-33655 GHSA-6qcr-qxgr-m7fv
  • GO-2026-5933 GHSA-3g4q-2f67-2gvh
  • GO-2026-5934 GHSA-59qp-cfj3-rp64
  • GO-2026-5935 GHSA-7856-g3gv-9wq8
  • GO-2026-5936 CVE-2026-53552 GHSA-26rh-24rg-j3vv
  • GO-2026-5937 CVE-2026-53508 GHSA-2jcc-mxv7-p3f9
  • GO-2026-5938 CVE-2026-53553 GHSA-4g5x-hcwm-82jw
  • GO-2026-5939 CVE-2026-10517 GHSA-698x-9w2p-7vvp
  • GO-2026-5940 CVE-2026-53572 GHSA-6w3m-4hhp-775q
  • GO-2026-5941 CVE-2026-53487 GHSA-gvhc-wv3v-7pf8
  • GO-2026-5942 CVE-2026-46600
  • GO-2026-5944 CVE-2026-50197 GHSA-659f-rgp5-w4wf
  • GO-2026-5945 CVE-2026-6815 GHSA-rmxx-v9rj-vpvg
  • GO-2026-5946 CVE-2026-52831 GHSA-v5px-423j-pf7p
  • GO-2026-5947 CVE-2026-53649 GHSA-xqhv-chqm-fhcc
  • GO-2026-5948 CVE-2026-50554 GHSA-588f-fvcv-xhvf
  • GO-2026-5949 CVE-2026-50553 GHSA-rqrh-8wpv-x7hh
  • GO-2026-5950 CVE-2026-53602 GHSA-339v-266x-79xr
  • GO-2026-5951 CVE-2026-10219 GHSA-6jm8-4fhr-5w64
  • GO-2026-5952 CVE-2026-49834 GHSA-9vcr-p3rj-q5q6
  • GO-2026-5953 CVE-2026-9094 GHSA-c9w5-qp6m-m395
  • GO-2026-5956 CVE-2026-55252 GHSA-h5g6-xmh4-hc37
  • GO-2026-5957 CVE-2026-54158 GHSA-5xfx-xj4h-5p7r
  • GO-2026-5958 CVE-2026-54068 GHSA-gcm7-57gf-953c
  • GO-2026-5959 CVE-2026-54072 GHSA-h29v-hj44-q8cv
  • GO-2026-5961 CVE-2026-54069 GHSA-hvr9-72v2-fff3
  • GO-2026-5962 CVE-2026-54088 GHSA-m93h-4hw7-5qcm
  • GO-2026-5963 CVE-2026-54067 GHSA-mvjr-vv3c-w4qv
  • GO-2026-5964 CVE-2026-54066 GHSA-p4m3-mgmm-c664
  • GO-2026-5965 CVE-2026-54070 GHSA-w7cg-whh7-xp28
  • GO-2026-5966 CVE-2026-54089 GHSA-xqp3-jq6g-x3qm
  • GO-2026-5967 CVE-2026-50551 GHSA-56mp-4f3v-fgj2
  • GO-2026-5968 CVE-2026-54174 GHSA-fpg8-7664-jc5q
  • GO-2026-5969 GHSA-g936-7jqj-mwv8
  • GO-2026-5970 CVE-2026-56852
  • GO-2026-5973 CVE-2026-54250 GHSA-jxr7-mqhw-9p98
  • GO-2026-5974 CVE-2026-44300 GHSA-wmj8-9953-vff5
  • GO-2026-5975 CVE-2026-50018 GHSA-42j2-w334-qxw7
  • GO-2026-5976 CVE-2026-50141 GHSA-g7mm-9vx7-jm7h
  • GO-2026-5977 CVE-2026-50013 GHSA-qrh4-p6v4-mrfg
  • GO-2026-5978 CVE-2026-50125 GHSA-qw5r-ppcg-f8rj
  • GO-2026-5979 CVE-2026-50006 GHSA-xrcf-6jh3-ggvx
  • GO-2026-5980 CVE-2026-50158 GHSA-2c7f-fxww-6w6c
  • GO-2026-5981 GHSA-mqxv-9rm6-w8qc
  • GO-2026-5982 GHSA-pqg7-v6wh-3pfp
  • GO-2026-5984 CVE-2026-53604 GHSA-2p2f-px33-4vv5
  • GO-2026-5985 GHSA-7rx3-5wx3-5v76
  • GO-2026-5986 CVE-2026-61699 GHSA-cm26-5974-52h8
  • GO-2026-5987 CVE-2026-55513 GHSA-g4x6-jcvr-9m3g
  • GO-2026-5988 CVE-2026-54628 GHSA-hwrq-8wxh-q4xv
  • GO-2026-5989 CVE-2026-55512 GHSA-m3cx-mwpg-32jg
  • GO-2026-5990 CVE-2026-54629 GHSA-mf78-3rpf-r784
  • GO-2026-5991 CVE-2026-53603 GHSA-q4vm-pq3q-8wgq
  • GO-2026-5992 CVE-2026-61549 GHSA-qf34-295c-26v8
  • GO-2026-5996 CVE-2026-54450 GHSA-pph6-vfjv-vpjw
  • GO-2026-5997 CVE-2026-54452 GHSA-xgch-x3mx-cm3c
  • GO-2026-5998 CVE-2026-54495 GHSA-398h-7f66-3h4p
  • GO-2026-5999 CVE-2026-10814 GHSA-jh6h-v6mp-h22v
  • GO-2026-6002 CVE-2026-58196 GHSA-pr64-jmmf-jp54
  • GO-2026-6003 CVE-2026-53714 GHSA-22xc-xg2r-9j7v
  • GO-2026-6004 CVE-2026-52833 GHSA-3v79-m2cg-89ww
  • GO-2026-6005 CVE-2026-53715 GHSA-8fv2-88gg-hm7q
  • GO-2026-6006 CVE-2026-53716 GHSA-cxpq-8v7q-cg56 *…
Record
openSUSE-SU-2026:21483-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
github.com/kata-containers/kata-containers
Go
 before 0.0.0-20260422180503-1b9e49eb2763
0.0.0-20260422180503-1b9e49eb2763
govulncheck-vulndb
openSUSE:Leap 16.0
From an advisory covering 1734 CVEs
 before 0.0.20260723T184607-160000.1.1
0.0.20260723T184607-160000.1.1

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

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

In short

CVE-2026-41326 is a high vulnerability (CVSS 8.2) in Katacontainers Kata Containers, published April 24, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.35%, the 28th percentile. Fixed in github.com/kata-containers/kata-containers 0.0.0-20260422180503-1b9e49eb2763.

References

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