CVE-2020-35684
No exploitation reported by the sources we read.
- Published2021-08-19
- WeaknessCWE-20
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
Description
An issue was discovered in HCC Nichestack 3.0. The code that parses TCP packets relies on an unchecked value of the IP payload size (extracted from the IP header) to compute the length of the TCP payload within the TCP checksum computation function. When the IP payload size is set to be smaller than the size of the IP header, the TCP checksum computation function may read out of bounds (a low-impact write-out-of-bounds is also possible).
Timeline
dates in UTC- 2021-08-1912:15CVE publishedNVD
Observed activity
isMalicious corpus · updated 2026-10-23 18:48 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2020-35684?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-35684?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
NVD| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 3.0 | = 3.0 | no fix published | NVD |
| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 2.0 | < 2.0.0 | 2.0.0 | NVD |
| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 1.2 | < 1.2.0 | 1.2.0 | NVD |
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Distribution builds and vendor advisories
Packages from OSV.dev and products from the vendors' CSAF advisories.
version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.
Vendor advisories
HCC Embedded InterNiche TCP/IP stack, NicheLite (Update B)
InterNiche stack: All versions prior to v4.3 · NicheLite: All versions prior to v4.3
Fix
- Vendor fix CISA ICSA-21-217-01 · 2 productsHCC recommends users apply release v4.3 or later to mitigate these vulnerabilities. For more information, contact HCC.
- Vendor fix CISA ICSA-21-217-01 · 2 productsAdditional vendors affected by the reported vulnerabilities have also released security advisories related to their affected products. Those advisories are as follows:
Advisories and patches
- cert-portal.siemens.comMitigation
- www.forescout.comMitigation
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
Sources
- NVDCVSS 3.17.5read 2026-10-23
- NVDCVSS 2.05read 2026-10-23
- NVDweakness (CWE)CWE-20read 2026-10-23
- FIRST EPSSEPSS score2.3 %2026-10-22
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Published
- 2021-08-19
- Last Modified
- 2026-06-17
- NVD status
- Modified
Frequently asked questions
What is CVE-2020-35684?
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