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CVE-2021-35977· NVD / CVE Program· CNA mitre

An issue was discovered in Digi RealPort for Windows through 4.8.488.0.

An issue was discovered in Digi RealPort for Windows through 4.8.488.0. A buffer overflow exists in the handling of ADDP discovery response messages. This could result in arbitrary code execution.

CriticalCVSS 9.8 · v3.1—No exploit No fix recorded

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Published
Oct 8, 2021
Updated
Jun 16, 2026
EPSS
1.6% · 75th percentile
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Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.6%

Affected systems

VendorProduct
digirealport
digiconnectport ts 8\/16 firmware
digiconnectport ts 8\/16
digiconnectport lts 8\/16\/32 firmware
digiconnectport lts 8\/16\/32
digipassport integrated console server firmware
digipassport integrated console server
digicm firmware
digicm
digiportserver ts firmware
digiportserver ts
digiportserver ts mei firmware

and 23 more

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • digi 6350-sr firmwareall versions
  • digi cm firmwareall versions
  • digi connect es firmwareall versions
  • digi connectport lts 8/16/32 firmwareall versions
  • digi connectport ts 8/16 firmwareall versions
  • digi one ia firmwareall versions
  • digi one iap family firmwareall versions
  • digi passport integrated console server firmwareall versions
  • digi portserver ts firmwareall versions
  • digi portserver ts m mei firmwareall versions
  • digi portserver ts mei firmwareall versions
  • digi portserver ts mei hardened firmwareall versions
  • digi portserver ts p mei firmwareall versions
  • digi realportup to 1.9-40 inclusive
  • digi realportup to 4.8.488.0 inclusive
  • digi transport wr11 xt firmwareall versions
  • digi wr21 firmwareall versions
  • digi wr31 firmwareall versions
  • digi wr44 r firmwareall versions

Same product

digi: all records

Other highest-scoring records for the same primary product.

  • CVE-2021-36767In Digi RealPort through 4.10.490, authentication relies on a challenge-response mechanism that gives access to the server password, making
    39Monitor
  • CVE-2023-4299Digi RealPort Protocol Use of Password Hash Instead of Password for Authentication
    32Monitor
  • CVE-2021-35979An issue was discovered in Digi RealPort through 4.8.488.0.
    32Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-120 · Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Root cause

When data is copied, the source length is not compared with the size of the destination buffer. Excess data overwrites adjacent memory.

The bug in code

The whole CWE-120 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

c
char buf[256];memcpy(buf, pkt->data, pkt->len);

Fixed

c
char buf[256];if (pkt->len > sizeof(buf)) {  return -EINVAL;}memcpy(buf, pkt->data, pkt->len);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records