What’s Vulnerable › Vulnerabilities

CVE-2020-35684

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-08-19 · updated 2026-06-17
• Weakness: CWE-20

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).

Affected products

• Hcc-Embedded Nichestack: 3.0
• Siemens Sentron 3Wa Com190 Firmware: before 2.0.0 — fixed in 2.0.0
• Siemens Sentron 3Wl Com35 Firmware: before 1.2.0 — fixed in 1.2.0

How to fix

Upgrade to a fixed version: Siemens Sentron 3Wa Com190 Firmware 2.0.0; Siemens Sentron 3Wl Com35 Firmware 1.2.0. Check the vendor advisory for mitigations.

References

• https://cert-portal.siemens.com/productcert/pdf/ssa-789208.pdf
• https://www.forescout.com/blog/new-critical-operational-technology-vulnerabilities-found-on-nichestack/
• https://www.hcc-embedded.com
• https://www.kb.cert.org/vuls/id/608209
• https://cert-portal.siemens.com/productcert/pdf/ssa-789208.pdf
• https://www.forescout.com/blog/new-critical-operational-technology-vulnerabilities-found-on-nichestack/
• https://www.hcc-embedded.com
• https://www.kb.cert.org/vuls/id/608209

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