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CVE-2021-3735

A deadlock issue was found in the AHCI controller device of QEMU. It occurs on a software reset ...

4.4 MediumFix available

A deadlock issue was found in the AHCI controller device of QEMU. It occurs on a software reset (ahci_reset_port) while handling a host-to-device Register FIS (Frame Information Structure) packet from the guest. A privileged user inside the guest could use this flaw to hang the QEMU process on the host, resulting in a denial of service condition. The highest threat from this vulnerability is to system availability.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
High
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.21%Down 0.7 points since Aug 27, 2022
90%50%10%1%

What each source reports

NVD Score used 4.4

A deadlock issue was found in the AHCI controller device of QEMU. It occurs on a software reset (ahci_reset_port) while handling a host-to-device Register FIS (Frame Information Structure) packet from the guest. A privileged user inside the guest could use this flaw to hang the QEMU process on the host, resulting in a denial of service condition. The highest threat from this vulnerability is to system availability.

Record
CVE-2021-3735
CVSS 3.1
4.4 MediumCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-667, CWE-400
Updated
2026-11-02
CVE List No score

A deadlock issue was found in the AHCI controller device of QEMU. It occurs on a software reset (ahci_reset_port) while handling a host-to-device Register FIS (Frame Information Structure) packet from the guest. A privileged user inside the guest could use this flaw to hang the QEMU process on the host, resulting in a denial of service condition. The highest threat from this vulnerability is to system availability.

Record
CVE-2021-3735
Weakness
CWE-667
Updated
2026-11-02
EUVDEUVD-2021-27011 0.0

A deadlock issue was found in the AHCI controller device of QEMU. It occurs on a software reset (ahci_reset_port) while handling a host-to-device Register FIS (Frame Information Structure) packet from the guest. A privileged user inside the guest could use this flaw to hang the QEMU process on the host, resulting in a denial of service condition. The highest threat from this vulnerability is to system availability.

Record
EUVD-2021-27011
CVSS
0.0 NoneCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-ch7h-w2mm-gm7m 4.4

A deadlock issue was found in the AHCI controller device of QEMU. It occurs on a software reset ...

A deadlock issue was found in the AHCI controller device of QEMU. It occurs on a software reset (ahci_reset_port) while handling a host-to-device Register FIS (Frame Information Structure) packet from the guest. A privileged user inside the guest could use this flaw to hang the QEMU process on the host, resulting in a denial of service condition. The highest threat from this vulnerability is to system availability.

Record
GHSA-ch7h-w2mm-gm7m
CVSS 3.1
4.4 MediumCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-400, CWE-667
Updated
2026-11-02
OSVBELL-CVE-2021-3735 4.4
Record
BELL-CVE-2021-3735
CVSS 3.1
4.4 MediumCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSV 4.4

A deadlock issue was found in the AHCI controller device of QEMU. It occurs on a software reset (ahci_reset_port) while handling a host-to-device Register FIS (Frame Information Structure) packet from the guest. A privileged user inside the guest could use this flaw to hang the QEMU process on the host, resulting in a denial of service condition. The highest threat from this vulnerability is to system availability.

Record
CVE-2021-3735
CVSS 3.1
4.4 MediumCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2021-3735 4.4

A deadlock issue was found in the AHCI controller device of QEMU. It occurs on a software reset (ahci_reset_port) while handling a host-to-device Register FIS (Frame Information Structure) packet from the guest. A privileged user inside the guest could use this flaw to hang the QEMU process on the host, resulting in a denial of service condition. The highest threat from this vulnerability is to system availability.

Record
DEBIAN-CVE-2021-3735
CVSS 3.1
4.4 MediumCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2021-3735 4.4

A deadlock issue was found in the AHCI controller device of QEMU. It occurs on a software reset (ahci_reset_port) while handling a host-to-device Register FIS (Frame Information Structure) packet from the guest. A privileged user inside the guest could use this flaw to hang the QEMU process on the host, resulting in a denial of service condition. The highest threat from this vulnerability is to system availability.

Record
UBUNTU-CVE-2021-3735
CVSS 3.1
4.4 MediumCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
qemu
Alpaquita:stream
 8.0.2-r0 up to 8.1.0-r0
8.1.0-r0
qemu
Debian:12
 All versions, plus listed versions
1:10.0.0+ds-11:10.0.0+ds-21:10.0.0+ds-2~bpo12+11:10.0.0+ds-2~bpo12+21:10.0.0~rc0+ds-1
Show 45 moreShow less
1:10.0.0~rc0+ds-21:10.0.0~rc1+ds-11:10.0.0~rc1+ds-21:10.0.0~rc2+ds-11:10.0.0~rc2+ds-21:10.0.0~rc3+ds-11:10.0.0~rc3+ds-21:10.0.2+ds-11:10.0.2+ds-21:10.0.2+ds-2~bpo12+11:10.0.3+ds-11:10.0.3+ds-21:10.0.3+ds-31:10.0.3+ds-41:10.1.0+ds-11:10.1.0+ds-21:10.1.0+ds-31:10.1.0+ds-41:10.1.0+ds-51:10.1.0~rc0+ds-11:10.1.0~rc0+ds-21:10.1.0~rc0+ds-31:10.1.0~rc0+ds-41:10.1.0~rc1+ds-11:10.1.0~rc1+ds-1a1:10.1.0~rc1+ds-1b1:10.1.0~rc1+ds-21:10.1.0~rc1+ds-31:10.1.0~rc2+ds-11:10.1.0~rc3+ds-11:10.1.0~rc3+ds-21:10.1.1+ds-11:10.1.2+ds-11:10.1.2+ds-21:10.1.2+ds-31:10.1.3+ds-11:10.2.0+ds-11:10.2.0+ds-21:10.2.0~rc1+ds-11:10.2.1+ds-11:10.2.2+ds-11:11.0.0+ds-11:11.0.0+ds-21:11.0.0~rc0+ds-11:11.0.0~rc0+ds-2
 None known
qemu
Debian:13
 All versions, plus listed versions
1:10.0.10+ds-0+deb13u11:10.0.11+ds-0+deb13u11:10.0.13+ds-0+deb13u11:10.0.2+ds-21:10.0.2+ds-2+deb13u1
Show 45 moreShow less
1:10.0.2+ds-2+deb13u1~bpo12+11:10.0.3+ds-0+deb13u11:10.0.3+ds-11:10.0.3+ds-21:10.0.3+ds-31:10.0.3+ds-41:10.0.6+ds-0+deb13u11:10.0.6+ds-0+deb13u21:10.0.7+ds-0+deb13u11:10.0.8+ds-0+deb13u11:10.1.0+ds-11:10.1.0+ds-21:10.1.0+ds-31:10.1.0+ds-41:10.1.0+ds-51:10.1.0~rc0+ds-11:10.1.0~rc0+ds-21:10.1.0~rc0+ds-31:10.1.0~rc0+ds-41:10.1.0~rc1+ds-11:10.1.0~rc1+ds-1a1:10.1.0~rc1+ds-1b1:10.1.0~rc1+ds-21:10.1.0~rc1+ds-31:10.1.0~rc2+ds-11:10.1.0~rc3+ds-11:10.1.0~rc3+ds-21:10.1.1+ds-11:10.1.2+ds-11:10.1.2+ds-21:10.1.2+ds-31:10.1.3+ds-11:10.2.0+ds-11:10.2.0+ds-21:10.2.0~rc1+ds-11:10.2.1+ds-11:10.2.2+ds-11:11.0.0+ds-11:11.0.0+ds-21:11.0.0~rc0+ds-11:11.0.0~rc0+ds-21:11.0.0~rc1+ds-11:11.0.0~rc1+ds-21:11.0.0~rc1+ds-31:11.0.0~rc2+ds-1
 None known
qemu
Debian:14
 All versions, plus listed versions
1:10.0.2+ds-21:10.0.3+ds-11:10.0.3+ds-21:10.0.3+ds-31:10.0.3+ds-4
Show 45 moreShow less
1:10.1.0+ds-11:10.1.0+ds-21:10.1.0+ds-31:10.1.0+ds-41:10.1.0+ds-51:10.1.0~rc0+ds-11:10.1.0~rc0+ds-21:10.1.0~rc0+ds-31:10.1.0~rc0+ds-41:10.1.0~rc1+ds-11:10.1.0~rc1+ds-1a1:10.1.0~rc1+ds-1b1:10.1.0~rc1+ds-21:10.1.0~rc1+ds-31:10.1.0~rc2+ds-11:10.1.0~rc3+ds-11:10.1.0~rc3+ds-21:10.1.1+ds-11:10.1.2+ds-11:10.1.2+ds-21:10.1.2+ds-31:10.1.3+ds-11:10.2.0+ds-11:10.2.0+ds-21:10.2.0~rc1+ds-11:10.2.1+ds-11:10.2.2+ds-11:11.0.0+ds-11:11.0.0+ds-21:11.0.0~rc0+ds-11:11.0.0~rc0+ds-21:11.0.0~rc1+ds-11:11.0.0~rc1+ds-21:11.0.0~rc1+ds-31:11.0.0~rc2+ds-11:11.0.0~rc2+ds-21:11.0.0~rc3+ds-11:11.0.1+ds-11:11.0.2+ds-11:11.0.2+ds-21:11.0.2+ds-2~bpo13+11:11.0.3+ds-11:11.0.3+ds-21:11.1.0+ds-11:11.1.0+ds-2
 None known
qemu
Ubuntu:Pro:14.04:LTS
 All versions, plus listed versions
1.5.0+dfsg-3ubuntu51.5.0+dfsg-3ubuntu61.6.0+dfsg-2ubuntu11.6.0+dfsg-2ubuntu21.6.0+dfsg-2ubuntu3
Show 45 moreShow less
1.6.0+dfsg-2ubuntu41.7.0+dfsg-2ubuntu11.7.0+dfsg-2ubuntu21.7.0+dfsg-2ubuntu31.7.0+dfsg-2ubuntu41.7.0+dfsg-2ubuntu51.7.0+dfsg-2ubuntu71.7.0+dfsg-2ubuntu81.7.0+dfsg-2ubuntu91.7.0+dfsg-3ubuntu1~ppa11.7.0+dfsg-3ubuntu11.7.0+dfsg-3ubuntu21.7.0+dfsg-3ubuntu31.7.0+dfsg-3ubuntu41.7.0+dfsg-3ubuntu51.7.0+dfsg-3ubuntu61.7.0+dfsg-3ubuntu72.0.0~rc1+dfsg-0ubuntu12.0.0~rc1+dfsg-0ubuntu22.0.0~rc1+dfsg-0ubuntu32.0.0~rc1+dfsg-0ubuntu3.12.0.0+dfsg-2ubuntu12.0.0+dfsg-2ubuntu1.12.0.0+dfsg-2ubuntu1.22.0.0+dfsg-2ubuntu1.32.0.0+dfsg-2ubuntu1.52.0.0+dfsg-2ubuntu1.62.0.0+dfsg-2ubuntu1.72.0.0+dfsg-2ubuntu1.82.0.0+dfsg-2ubuntu1.92.0.0+dfsg-2ubuntu1.102.0.0+dfsg-2ubuntu1.112.0.0+dfsg-2ubuntu1.132.0.0+dfsg-2ubuntu1.142.0.0+dfsg-2ubuntu1.152.0.0+dfsg-2ubuntu1.162.0.0+dfsg-2ubuntu1.172.0.0+dfsg-2ubuntu1.182.0.0+dfsg-2ubuntu1.192.0.0+dfsg-2ubuntu1.202.0.0+dfsg-2ubuntu1.212.0.0+dfsg-2ubuntu1.222.0.0+dfsg-2ubuntu1.242.0.0+dfsg-2ubuntu1.252.0.0+dfsg-2ubuntu1.26
 None known
qemu
Ubuntu:Pro:16.04:LTS
 All versions, plus listed versions
1:2.3+dfsg-5ubuntu91:2.3+dfsg-5ubuntu101:2.4+dfsg-4ubuntu11:2.4+dfsg-4ubuntu21:2.4+dfsg-4ubuntu3
Show 45 moreShow less
1:2.4+dfsg-5ubuntu31:2.5+dfsg-1ubuntu21:2.5+dfsg-1ubuntu31:2.5+dfsg-1ubuntu41:2.5+dfsg-1ubuntu51:2.5+dfsg-5ubuntu11:2.5+dfsg-5ubuntu21:2.5+dfsg-5ubuntu41:2.5+dfsg-5ubuntu61:2.5+dfsg-5ubuntu71:2.5+dfsg-5ubuntu101:2.5+dfsg-5ubuntu10.11:2.5+dfsg-5ubuntu10.21:2.5+dfsg-5ubuntu10.31:2.5+dfsg-5ubuntu10.41:2.5+dfsg-5ubuntu10.51:2.5+dfsg-5ubuntu10.61:2.5+dfsg-5ubuntu10.71:2.5+dfsg-5ubuntu10.81:2.5+dfsg-5ubuntu10.91:2.5+dfsg-5ubuntu10.101:2.5+dfsg-5ubuntu10.111:2.5+dfsg-5ubuntu10.131:2.5+dfsg-5ubuntu10.141:2.5+dfsg-5ubuntu10.151:2.5+dfsg-5ubuntu10.161:2.5+dfsg-5ubuntu10.201:2.5+dfsg-5ubuntu10.211:2.5+dfsg-5ubuntu10.221:2.5+dfsg-5ubuntu10.241:2.5+dfsg-5ubuntu10.251:2.5+dfsg-5ubuntu10.261:2.5+dfsg-5ubuntu10.281:2.5+dfsg-5ubuntu10.291:2.5+dfsg-5ubuntu10.301:2.5+dfsg-5ubuntu10.311:2.5+dfsg-5ubuntu10.321:2.5+dfsg-5ubuntu10.331:2.5+dfsg-5ubuntu10.341:2.5+dfsg-5ubuntu10.351:2.5+dfsg-5ubuntu10.361:2.5+dfsg-5ubuntu10.371:2.5+dfsg-5ubuntu10.381:2.5+dfsg-5ubuntu10.391:2.5+dfsg-5ubuntu10.40
 None known
qemu
Ubuntu:Pro:18.04:LTS
 All versions, plus listed versions
1:2.10+dfsg-0ubuntu31:2.10+dfsg-0ubuntu41:2.10+dfsg-0ubuntu51:2.11+dfsg-1ubuntu11:2.11+dfsg-1ubuntu2
Show 45 moreShow less
1:2.11+dfsg-1ubuntu41:2.11+dfsg-1ubuntu51:2.11+dfsg-1ubuntu61:2.11+dfsg-1ubuntu71:2.11+dfsg-1ubuntu7.11:2.11+dfsg-1ubuntu7.21:2.11+dfsg-1ubuntu7.31:2.11+dfsg-1ubuntu7.41:2.11+dfsg-1ubuntu7.51:2.11+dfsg-1ubuntu7.61:2.11+dfsg-1ubuntu7.71:2.11+dfsg-1ubuntu7.81:2.11+dfsg-1ubuntu7.91:2.11+dfsg-1ubuntu7.101:2.11+dfsg-1ubuntu7.121:2.11+dfsg-1ubuntu7.131:2.11+dfsg-1ubuntu7.141:2.11+dfsg-1ubuntu7.151:2.11+dfsg-1ubuntu7.171:2.11+dfsg-1ubuntu7.181:2.11+dfsg-1ubuntu7.191:2.11+dfsg-1ubuntu7.201:2.11+dfsg-1ubuntu7.211:2.11+dfsg-1ubuntu7.221:2.11+dfsg-1ubuntu7.231:2.11+dfsg-1ubuntu7.251:2.11+dfsg-1ubuntu7.261:2.11+dfsg-1ubuntu7.271:2.11+dfsg-1ubuntu7.281:2.11+dfsg-1ubuntu7.291:2.11+dfsg-1ubuntu7.311:2.11+dfsg-1ubuntu7.321:2.11+dfsg-1ubuntu7.331:2.11+dfsg-1ubuntu7.341:2.11+dfsg-1ubuntu7.351:2.11+dfsg-1ubuntu7.361:2.11+dfsg-1ubuntu7.371:2.11+dfsg-1ubuntu7.381:2.11+dfsg-1ubuntu7.391:2.11+dfsg-1ubuntu7.401:2.11+dfsg-1ubuntu7.411:2.11+dfsg-1ubuntu7.421:2.11+dfsg-1ubuntu7.42+esm11:2.11+dfsg-1ubuntu7.42+esm21:2.11+dfsg-1ubuntu7.42+esm5
 None known
qemu
Ubuntu:Pro:20.04:LTS
 All versions, plus listed versions
1:4.0+dfsg-0ubuntu91:4.0+dfsg-0ubuntu101:4.2-1ubuntu11:4.2-1ubuntu21:4.2-3ubuntu1
Show 35 moreShow less
1:4.2-3ubuntu21:4.2-3ubuntu31:4.2-3ubuntu41:4.2-3ubuntu51:4.2-3ubuntu61:4.2-3ubuntu6.11:4.2-3ubuntu6.21:4.2-3ubuntu6.31:4.2-3ubuntu6.41:4.2-3ubuntu6.51:4.2-3ubuntu6.61:4.2-3ubuntu6.71:4.2-3ubuntu6.81:4.2-3ubuntu6.91:4.2-3ubuntu6.101:4.2-3ubuntu6.111:4.2-3ubuntu6.121:4.2-3ubuntu6.141:4.2-3ubuntu6.151:4.2-3ubuntu6.161:4.2-3ubuntu6.171:4.2-3ubuntu6.181:4.2-3ubuntu6.191:4.2-3ubuntu6.211:4.2-3ubuntu6.231:4.2-3ubuntu6.241:4.2-3ubuntu6.251:4.2-3ubuntu6.261:4.2-3ubuntu6.271:4.2-3ubuntu6.281:4.2-3ubuntu6.291:4.2-3ubuntu6.301:4.2-3ubuntu6.30+esm11:4.2-3ubuntu6.30+esm21:4.2-3ubuntu6.30+esm3
 None known
qemu
Ubuntu:22.04:LTS
 All versions, plus listed versions
1:6.0+dfsg-2expubuntu11:6.0+dfsg-2expubuntu21:6.0+dfsg-2expubuntu41:6.2+dfsg-2ubuntu51:6.2+dfsg-2ubuntu6
Show 30 moreShow less
1:6.2+dfsg-2ubuntu6.11:6.2+dfsg-2ubuntu6.21:6.2+dfsg-2ubuntu6.31:6.2+dfsg-2ubuntu6.41:6.2+dfsg-2ubuntu6.51:6.2+dfsg-2ubuntu6.61:6.2+dfsg-2ubuntu6.71:6.2+dfsg-2ubuntu6.81:6.2+dfsg-2ubuntu6.91:6.2+dfsg-2ubuntu6.101:6.2+dfsg-2ubuntu6.111:6.2+dfsg-2ubuntu6.121:6.2+dfsg-2ubuntu6.131:6.2+dfsg-2ubuntu6.141:6.2+dfsg-2ubuntu6.151:6.2+dfsg-2ubuntu6.161:6.2+dfsg-2ubuntu6.171:6.2+dfsg-2ubuntu6.181:6.2+dfsg-2ubuntu6.191:6.2+dfsg-2ubuntu6.211:6.2+dfsg-2ubuntu6.221:6.2+dfsg-2ubuntu6.231:6.2+dfsg-2ubuntu6.241:6.2+dfsg-2ubuntu6.251:6.2+dfsg-2ubuntu6.261:6.2+dfsg-2ubuntu6.271:6.2+dfsg-2ubuntu6.281:6.2+dfsg-2ubuntu6.291:6.2+dfsg-2ubuntu6.301:6.2+dfsg-2ubuntu6.31
 None known
qemu
Ubuntu:24.04:LTS
 All versions, plus listed versions
1:8.0.4+dfsg-1ubuntu31:8.0.4+dfsg-1ubuntu41:8.0.4+dfsg-1ubuntu51:8.1.3+ds-1ubuntu21:8.2.1+ds-1ubuntu1
Show 19 moreShow less
1:8.2.1+ds-1ubuntu81:8.2.1+ds-1ubuntu91:8.2.2+ds-0ubuntu11:8.2.2+ds-0ubuntu1.21:8.2.2+ds-0ubuntu1.41:8.2.2+ds-0ubuntu1.51:8.2.2+ds-0ubuntu1.61:8.2.2+ds-0ubuntu1.71:8.2.2+ds-0ubuntu1.81:8.2.2+ds-0ubuntu1.91:8.2.2+ds-0ubuntu1.101:8.2.2+ds-0ubuntu1.111:8.2.2+ds-0ubuntu1.121:8.2.2+ds-0ubuntu1.131:8.2.2+ds-0ubuntu1.141:8.2.2+ds-0ubuntu1.151:8.2.2+ds-0ubuntu1.161:8.2.2+ds-0ubuntu1.171:8.2.2+ds-0ubuntu1.18
 None known
Show 5 moreShow less
Affected packages
PackageAffectedFixed
qemu
Ubuntu:25.10
 All versions, plus listed versions
1:9.2.1+ds-1ubuntu51:10.0.2+ds-1ubuntu11:10.0.2+ds-1ubuntu21:10.1.0+ds-1ubuntu11:10.1.0+ds-5ubuntu1
Show 7 moreShow less
1:10.1.0+ds-5ubuntu21:10.1.0+ds-5ubuntu2.11:10.1.0+ds-5ubuntu2.21:10.1.0+ds-5ubuntu2.41:10.1.0+ds-5ubuntu2.51:10.1.0+ds-5ubuntu2.61:10.1.0+ds-5ubuntu2.7
 None known
qemu
Ubuntu:26.10
 All versions, plus listed versions
1:10.2.1+ds-1ubuntu31:10.2.1+ds-1ubuntu61:11.0.3+ds-2ubuntu11:11.0.3+ds-2ubuntu2
 None known
qemu-hwe
Ubuntu:26.10
 All versions, plus listed versions
1:10.2.1+ds-1ubuntu41:10.2.1+ds-1ubuntu71:10.2.1+ds-1ubuntu81:11.0.3+ds-2ubuntu21:11.0.3+ds-2ubuntu4
 None known
qemu
Ubuntu:26.04:LTS
 All versions, plus listed versions
1:10.1.0+ds-5ubuntu21:10.1.0+ds-5ubuntu31:10.1.0+ds-5ubuntu41:10.1.0+ds-5ubuntu51:10.2.1+ds-1ubuntu1
Show 5 moreShow less
1:10.2.1+ds-1ubuntu21:10.2.1+ds-1ubuntu31:10.2.1+ds-1ubuntu3.11:10.2.1+ds-1ubuntu3.21:10.2.1+ds-1ubuntu3.3
 None known
qemu-hwe
Ubuntu:26.04:LTS
 All versions, plus listed versions
1:10.2.1+ds-1ubuntu21:10.2.1+ds-1ubuntu41:10.2.1+ds-1ubuntu4.21:10.2.1+ds-1ubuntu4.31:10.2.1+ds-1ubuntu4.4
 None known

History

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

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

In short

CVE-2021-3735 is a medium vulnerability (CVSS 4.4) in Qemu, published August 26, 2022. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.21%, the 10th percentile. Fixed in qemu 8.1.0-r0.

References

This page doesn't list everything

Left out here: 232 versions. The JSON record has them.

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