CVE-2020-35684
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).
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (2.29%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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).
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 2.29% probability · 83th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-20
- Affected
- hcc-embedded/nichestack · siemens/sentron 3wl com35 firmware · siemens/sentron 3wa com190 firmware
- Source
- cve@mitre.org
EPSS 2.3% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://cert-portal.siemens.com/productcert/pdf/ssa-789208.pdfMitigation, Third Party Advisory
- https://www.forescout.com/blog/new-critical-operational-technology-vulnerabilities-found-on-nichestack/Mitigation, Third Party Advisory
- https://www.hcc-embedded.comProduct
- https://www.kb.cert.org/vuls/id/608209Third Party Advisory, US Government Resource
- https://cert-portal.siemens.com/productcert/pdf/ssa-789208.pdfMitigation, Third Party Advisory
- https://www.forescout.com/blog/new-critical-operational-technology-vulnerabilities-found-on-nichestack/Mitigation, Third Party Advisory
- https://www.hcc-embedded.comProduct
- https://www.kb.cert.org/vuls/id/608209Third Party Advisory, US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.