CVE-2020-8835Linux kernel bpf verifier vulnerability
- 7.8HighCVSS base score
- 6.0%Exploitation in 30 daysEPSS · top 6.5% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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)
Timeline
ID reserved
By canonical
- 52 days later
· 52 days later
Published
- 4 years later
· 4 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| canonicalCNA (assigner) | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H |
| NVDNVD · Modified | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 6.0% · top 6.5% of all CVEs (14 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.
Affected products
- affected 5.6-stable – < 5.6.1
- affected 5.5-stable – < 5.5.14
- affected 5.4.7 – < 5.4-stable*
What to do
Solution: Revert commit 581738a681b6 ("bpf: Provide better register bounds after jmp32 instructions").
Workaround: Mitigation for this vulnerability is available by setting the kernel.unprivileged_bpf_disabled sysctl to 1: $ sudo sysctl kernel.unprivileged_bpf_disabled=1 $ echo kernel.unprivileged_bpf_disabled=1 | sudo tee /etc/sysctl.d/90-CVE-2020-8835.conf This issue is also mitigated on systems that use secure boot with the kernel lockdown feature which blocks BPF program loading.
References
References12
- USN-4313-1 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
- https://www.thezdi.com/blog/2020/3/19/pwn2own-2020-day-one-results (opens in a new tab)x_refsource_MISCx_transferred
- https://lore.kernel.org/bpf/20200330160324.15259-1-daniel%40iogearbox.net/T/ (opens in a new tab)x_refsource_MISCx_transferred
- https://www.openwall.com/lists/oss-security/2020/03/30/3 (opens in a new tab)x_refsource_MISCx_transferred
- https://usn.ubuntu.com/usn/usn-4313-1 (opens in a new tab)x_refsource_MISCx_transferred
- https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=f2d67fec0b43edce8c416101cdc52e71145b5fef (opens in a new tab)x_refsource_MISCx_transferred
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f2d67fec0b43edce8c416101cdc52e71145b5fef (opens in a new tab)x_refsource_MISCx_transferred
- FEDORA-2020-4ef0bcc89c (opens in a new tab)vendor-advisoryx_refsource_FEDORAx_transferred
- FEDORA-2020-666f3b1ac3 (opens in a new tab)vendor-advisoryx_refsource_FEDORAx_transferred
- FEDORA-2020-73c00eda1c (opens in a new tab)vendor-advisoryx_refsource_FEDORAx_transferred
- https://security.netapp.com/advisory/ntap-20200430-0004/ (opens in a new tab)x_refsource_CONFIRMx_transferred
- [oss-security] 20210720 CVE-2021-33909: size_t-to-int vulnerability in Linux's filesystem layer (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2020-29678 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2020-8835)Record last updated .