CVE-2020-8835
Linux kernel bpf verifier vulnerability
Public exploit available. Not confirmed exploited in the wild yet. A vendor fix is available.
What to do
The vendor has published a fix. Version details are below where the sources state them.
What it is
From the CVE record
In the Linux kernel 5.5.0 and newer, the bpf verifier (kernel/bpf/verifier.c) did not properly restrict the register bounds for 32-bit operations, leading to out-of-bounds reads and writes in kernel memory. The vulnerability also affects the Linux 5.4 stable series, starting with v5.4.7, as the introducing commit was backported to that branch. This vulnerability was fixed in 5.6.1, 5.5.14, and 5.4.29. (issue is aka ZDI-CAN-10780)
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
1 source with a proof of concept or module.
Exploit links, PoCs and Metasploit modules after sign-in- EPSS
6.0% chance of exploitation activity in the next 30 days, which ranks it in the 93rd percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
The patch came 471 days before any public exploit.
- OpenVAS check added
- EPSS band changemoderate → low
- Public exploit / PoCsource: other
- Patch availableworkaround available, record updated
- Publishedweakness classified, att&ck mapped
Affected products
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Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Scored 7.8 by NVD.
How it is reached
- Attack Vector LocalRequires local access to the vulnerable system (e.g. local login, malicious file)
- Attack Complexity HighRequires specific conditions like a race condition or non-default configuration
- Privileges Required LowRequires basic user-level privileges
- User Interaction NoneNo user interaction needed — fully automated exploitation
Scope
- Scope ChangedThe exploit can affect other components (e.g. sandbox escape, host compromise from VM)
Impact if exploited
- Confidentiality HighTotal information disclosure — all data in the component is compromised
- Integrity HighTotal loss of integrity — attacker can modify any data in the component
- Availability HighTotal denial of service — the component is completely unavailable
Weaknesses
ATT&CK techniques
Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.
- CollectionT1005Data from Local Systemmedium confidence
- Initial AccessT1190Exploit Public-Facing Applicationhigh confidence
- Privilege EscalationT1068Exploitation for Privilege Escalationhigh confidence
Sources
References in the record
- openwall.com/lists/oss-security/2021/07/20/1&
- access.redhat.com/security/cve/cve-2020-8835&
- bugzilla.redhat.com/show_bug.cgi?id=1817350&
And 37 more references. See all after sign-in
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