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CVE-2020-29569

27
FAUCET Score

CVE-2020-29569 is a use-after-free vulnerability in the Linux kernel's PV block backend, affecting Linux kernels through 5.10.1 when used with Xen through 4.14.x. A misbehaving guest can trigger a dom0 crash by rapidly connecting and disconnecting a block frontend, with potential for privilege escalation and information leaks. This vulnerability has a CVSS score of 8.8 (HIGH), indicating a local attack vector with low complexity, leading to high impact on confidentiality, integrity, and availability. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
<= 4.14.1CPE matchmatch criteria
cpe:2.3:o:xen:xen:*:*:*:*:*:*:*:*
>= 4.1.44, < 4.2CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
>= 4.4.80, < 4.4.254CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
>= 4.9.36, < 4.9.249CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
>= 4.11.9, < 4.12CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.8HIGH

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

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.0
Impact Score
6.0
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.39%
Probability of exploitation in next 30 days
EPSS Percentile
31.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0039 is in the 70th percentile among its peer group of 16,994 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.2 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (8)

microsoftpatch availablevia msrc
Product: 19137-16820Fixed in: 5.4.91-1
microsoftpatch availablevia msrc
Product: cm1 kernel 5.4.91-1 on CBL Mariner 1.0Fixed in: 5.4.91-1
capnprotovendor investigatingvia llm_extracted
gcpvendor investigatingvia llm_extracted
hanwhavendor investigatingvia llm_extracted
kongvendor investigatingvia llm_extracted
openwrtvendor investigatingvia llm_extracted
proxmoxvendor investigatingvia llm_extracted

Vendor Advisories (7)

gcpllm-gcp-01a119d0ea3516faCRITICAL

ctrlX Multiple Vulnerabilities

Apr 23, 2021
capnprotollm-capnproto-5feb06313b602a85HIGH

ctrlX Multiple Vulnerabilities

Apr 23, 2021
openwrtllm-openwrt-b814c0e383a6a281CRITICAL

ctrlX Multiple Vulnerabilities

Apr 23, 2021
proxmoxllm-proxmox-202933dd58ce3ba3CRITICAL

ctrlX Multiple Vulnerabilities

Apr 23, 2021
kongllm-kong-7933c1edf7557da9CRITICAL

ctrlX Multiple Vulnerabilities

Apr 23, 2021
hanwhallm-hanwha-0b610f8bff10f748CRITICAL

ctrlX Multiple Vulnerabilities

Apr 23, 2021
microsoft2020-Dec/CVE-2020-29569Important

An issue was discovered in the Linux kernel through 5.10.1 as used with Xen through 4.14.x. The Linux kernel PV block backend expects the kernel thread handler to reset ring->xenblkd to NULL when stopped. However the handler may not have time to run if the frontend quickly toggles between the states connect and disconnect. As a consequence the block backend may re-use a pointer after it was freed. A misbehaving guest can trigger a dom0 crash by continuously connecting / disconnecting a block frontend. Privilege escalation and information leaks cannot be ruled out. This only affects systems with a Linux blkback.

Dec 8, 2020

References

lists.debian.org / debian-lts-announce/2021/02/msg00018.html
Mailing ListThird Party Advisory
lists.debian.org / debian-lts-announce/2021/03/msg00010.html
Mailing ListThird Party Advisory
security.gentoo.org / glsa/202107-30
Third Party Advisory
security.netapp.com / advisory/ntap-20210205-0001
Third Party Advisory
debian.org / security/2021/dsa-4843
Third Party Advisory
xenbits.xenproject.org / xsa/advisory-350.html
PatchVendor Advisory