Guest-to-host memory disclosure via ICMPv6 length
Published Apr 1, 2022 · Updated Aug 3, 2024
An out-of-bounds read in libslirp in Red Hat QEMU-KVM 4.2.0-34 allows local users to disclose host memory through crafted ICMPv6 echo traffic. The icmp6_send_echoreply() function copies ip->ip_pl bytes without validating the IPv6 payload length, so a guest process can read beyond the packet buffer and return host-memory contents. Exploitation requires a low-privilege process inside a guest with ICMPv6 support enabled; the demonstrated impact is confidentiality loss without integrity or availability effects.
Summary
What happened
An out-of-bounds read in libslirp in Red Hat QEMU-KVM 4.2.0-34 allows local users to disclose host memory through crafted ICMPv6 echo traffic. The icmp6_send_echoreply() function copies ip->ip_pl bytes without validating the IPv6 payload length, so a guest process can read beyond the packet buffer and return host-memory contents. Exploitation requires a low-privilege process inside a guest with ICMPv6 support enabled; the demonstrated impact is confidentiality loss without integrity or availability effects.
The record
- CVE
- CVE-2021-20295
- Published
- Apr 1, 2022
- Updated
- Aug 3, 2024
- Vendor
- Red Hat
- Product
- QEMU-KVM
- Classifications
- CWE-125, T1203
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Apr 1, 2022CVE publishedPublication date reported by the CVE source.
- Aug 3, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=qemu-kvm 4.2.0-34
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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