Security readout for executives and security teams
Plain-English summary
This flaw can make certain industrial devices stop working when they receive malformed UDP network traffic. The business risk is operational disruption, not data theft. It matters most where affected Hilscher rcX RTOS-based devices or listed Pepperl+Fuchs Ethernet IO modules are reachable from broader networks.
Executive priority
Prioritize remediation for affected devices supporting production, safety, or critical operations. The known impact is denial of service, so urgency depends on how much business process depends on continuous device availability and whether the devices are network-exposed.
Technical view
Hilscher rcX RTOS before V2.1.14.1 fails to verify the actual UDP packet length against the length declared in the packet. Sources say this can cause denial of service on affected devices. The CVSS 3.1 score is 8.6 with network access, low complexity, no privileges, and high availability impact.
Likely exposure
Exposure is likely limited to environments using Hilscher rcX RTOS before V2.1.14.1 or the listed Pepperl+Fuchs ICE1-16 and ICE1-8 Ethernet IO module models. Risk increases if those devices accept UDP traffic from untrusted, flat, or poorly segmented networks.
Exploitation context
The source bundle does not identify public exploitation or CISA KEV listing. Treat exploitation as plausible because the CVSS vector indicates network reachability, low complexity, and no authentication, but do not assume active exploitation without additional evidence.
Researcher notes
Evidence supports a UDP length validation bug causing device denial of service. CWE-119 is listed, but sources provided do not include exploit details, proof-of-concept status, or complete product firmware fix mapping beyond rcX RTOS versions before V2.1.14.1.
Mitigation direction
- Inventory Hilscher rcX RTOS and listed Pepperl+Fuchs ICE1 devices.
- Check Hilscher and CERT@VDE guidance for fixed firmware or runtime versions.
- Prioritize devices running rcX RTOS before V2.1.14.1.
- Limit UDP reachability to affected devices where operationally feasible.
- Coordinate maintenance windows before updating industrial control assets.
Validation and detection
- Confirm device model and firmware or runtime version from asset records.
- Map network paths that can send UDP traffic to affected devices.
- Check whether listed Pepperl+Fuchs ICE1 models are deployed.
- Review logs for unexplained device resets or availability loss.
- Verify remediation status against vendor advisory versions.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-119: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-20988 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.6 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H3.94Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.6HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://kb.hilscher.com/display/ISMS/2019-04-10+Wrong+handling+of+the+UDP+checksumCVE reference · x_refsource_CONFIRM
- https://cert.vde.com/de-de/advisories/vde-2021-018CVE reference · x_refsource_CONFIRM
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.