NVD / CVE Program· CNA mitre

CVE-2021-35977: An issue was discovered in Digi RealPort for Windows through 4.8.488.0.

Noroxi assessment

Priority: Monitor (action score 39/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 1.5% (FIRST EPSS); higher than 75.4% of all records.
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.
According to the record, no fixed version is available yet.

Low priority for now. Update when a fix is released; follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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

Published: Oct 8, 2021
Updated: Jun 16, 2026
EPSS: 1.5% · 75th percentile
CWE: CWE-120

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 39 / 40 · 9.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 1.5%

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
No fixed version yet

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
digi	realport	cpe:2.3:a:digi:realport
digi	connectport ts 8\/16 firmware	cpe:2.3:o:digi:connectport_ts_8\/16_firmware
digi	connectport ts 8\/16	cpe:2.3:h:digi:connectport_ts_8\/16
digi	connectport lts 8\/16\/32 firmware	cpe:2.3:o:digi:connectport_lts_8\/16\/32_firmware
digi	connectport lts 8\/16\/32	cpe:2.3:h:digi:connectport_lts_8\/16\/32
digi	passport integrated console server firmware	cpe:2.3:o:digi:passport_integrated_console_server_firmware
digi	passport integrated console server	cpe:2.3:h:digi:passport_integrated_console_server
digi	cm firmware	cpe:2.3:o:digi:cm_firmware
digi	cm	cpe:2.3:h:digi:cm
digi	portserver ts firmware	cpe:2.3:o:digi:portserver_ts_firmware
digi	portserver ts	cpe:2.3:h:digi:portserver_ts
digi	portserver ts mei firmware	cpe:2.3:o:digi:portserver_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

DIGI Responsible Disclosure ProgramIntigriti · disclosure only (VDP)

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

1char buf[256];
2memcpy(buf, pkt->data, pkt->len);

Fixed

1char buf[256];
2if (pkt->len > sizeof(buf)) {
3  return -EINVAL;
4}
5memcpy(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.

Attack patterns (CAPEC)

ATT&CK techniques

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Change log

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

References

raw.githubusercontent.com/reidmefirst/vuln-disclosure/main/2021-02.txt

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

All records