OpenBSD kernel version <= 6.5 can be forced to create long chains of TCP SACK holes that causes very expensive calls to tcp_sack_option() for every incoming SACK packet which can lead to a denial of service
Published Aug 26, 2019
7.5
HIGHCVSS 3.1
EPSS 2.25%
Description
OpenBSD kernel version <= 6.5 can be forced to create long chains of TCP SACK holes that causes very expensive calls to tcp_sack_option() for every incoming SACK packet which can lead to a denial of service.
Affected products
- Vendor n/a Product OpenBSD Defaultn/a
- Version All, including latest - 6.5StatusaffectedConstraints-
- Version
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| n/a | OpenBSD | n/a |
|
No data.
No Red Hat product state for this CVE.
No package ranges for this CVE.
Remediation
No remediation recorded yet.
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
No CVSS v3.0 score for this CVE.
AV:N/AC:L/Au:N/C:N/I:N/A:P
This CVE is not in the KEV list.
No CISA SSVC assessment for this CVE yet.
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 3, 2026.
Score over time
2021–2026- EPSS v1
- EPSS v5
- EPSS v2
- EPSS v3
Percentile over time
- EPSS v1
- EPSS v5
- EPSS v2
- EPSS v3
Table of values (11 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 3, 2026 | 2.25% (0.02253) | 82.33th | v5 (v2026.06.15) |
| Sep 20, 2026 | 2.25% (0.02253) | 82.16th | v5 (v2026.06.15) |
| Jul 20, 2024 | 0.27% (0.00274) | 68.36th | v3 (v2023.03.01) |
| Feb 8, 2024 | 0.27% (0.00274) | 67.12th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.27% (0.00274) | 62.95th | v3 (v2023.03.01) |
| Mar 6, 2023 | 1.02% (0.01018) | 40.69th | v2 (v2022.01.01) |
| Apr 1, 2022 | 1.02% (0.01018) | 36.86th | v2 (v2022.01.01) |
| Mar 31, 2022 | 7.18% (0.07176) | 80.78th | v2 (v2022.01.01) |
| Jan 6, 2022 | 6.60% (0.06599) | 82.86th | v1 |
| Jan 5, 2022 | 1.55% (0.01550) | 73.94th | v5 (v2026.06.15) |
| Apr 14, 2021 | 1.29% (0.01294) | 0.00th | v1 |
References (5)
- https://ftp.openbsd.org/pub/OpenBSD/patches/6.5/common/006_tcpsack.patch.sig x_refsource_MISCExploitVendor Advisory
- https://github.com/openbsd/src/commit/ed8fdce754a5d8d14c09e989d8877707bd43906f x_refsource_MISCPatchThird Party Advisory
- https://research.checkpoint.com/tcp-sack-security-issue-in-openbsd-cve-2019-8460/ x_refsource_MISCExploitPatchPress/Media CoverageThird Party Advisory
- https://security.netapp.com/advisory/ntap-20190905-0001/ x_refsource_CONFIRMThird Party Advisory
- https://us-cert.cisa.gov/ics/advisories/icsa-19-253-03 x_refsource_MISC
| Link | Providers | Tags |
|---|---|---|
| https://ftp.openbsd.org/pub/OpenBSD/patches/6.5/common/006_tcpsack.patch.sig | x_refsource_MISCExploitVendor Advisory | |
| https://github.com/openbsd/src/commit/ed8fdce754a5d8d14c09e989d8877707bd43906f | x_refsource_MISCPatchThird Party Advisory | |
| https://research.checkpoint.com/tcp-sack-security-issue-in-openbsd-cve-2019-8460/ | x_refsource_MISCExploitPatchPress/Media CoverageThird Party Advisory | |
| https://security.netapp.com/advisory/ntap-20190905-0001/ | x_refsource_CONFIRMThird Party Advisory | |
| https://us-cert.cisa.gov/ics/advisories/icsa-19-253-03 | x_refsource_MISC |
Change history (0)
No recorded changes yet.