TP-Link TL-WR940N V3 and V4 with firmware 3.16.9 and earlier contain a buffer overflow via the dnsserver1 and dnsserver2 parameters at /user
Noroxi assessment
Priority: Monitor (action score 34/100)
- Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
- Probability of exploitation in the next 30 days: 6.5% (FIRST EPSS); higher than 93.7% of all records.
- Someone on the same network segment can trigger it. A low-privileged account is enough. 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
TP-Link TL-WR940N V3 and V4 with firmware 3.16.9 and earlier contain a buffer overflow via the dnsserver1 and dnsserver2 parameters at /userRpm/Wan6to4TunnelCfgRpm.htm. This vulnerability allows an authenticated attacker to execute arbitrary code on the remote device in the context of the root user.
- Published
- Jan 9, 2025
- Updated
- Jul 5, 2026
- EPSS
- 6.5% · 93th percentile
- CWE
- CWE-120
Report tools
Action score
34
Monitor
Low priority for now.
- CVSS
- 32 / 40 · 8.0 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 2 / 30 · 6.5%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- Proof of concept exists, no weaponized module
- No fixed version yet
If any of these changes, we'll tell you in the daily email digest.
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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.
We use this product, ask for helpAffected 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 |
|---|---|---|
| tp-link | tl-wr940n firmware | cpe:2.3:o:tp-link:tl-wr940n_firmware |
| tp-link | tl-wr940n | cpe:2.3:h:tp-link:tl-wr940n |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- tp-link tl-wr940n firmwareup to 3.16.9 inclusive
Same product
tp-link: all recordsOther highest-scoring records for the same primary product.
- CVE-2023-33538TP-Link TL-WR940N V2/V4, TL-WR841N V8/V10, and TL-WR740N V1/V2 was discovered to contain a command injection vulnerability via the componentKEV77This week
- CVE-2023-36355TP-Link TL-WR940N V4 was discovered to contain a buffer overflow via the ipStart parameter at /userRpm/WanDynamicIpV6CfgRpm.49Plan
- CVE-2019-6989TP-Link TL-WR940N is vulnerable to a stack-based buffer overflow, caused by improper bounds checking by the ipAddrDispose function.38Monitor
Published before and after this one in the same product
- ← EarlierCVE-2023-36358Jun 22, 2023 · TP-Link TL-WR940N V2/V3/V4, TL-WR941ND V5/V6, TL-WR743ND V1 and TL-WR841N V8 were discovered to contain a buffer overflow in the component /30Monitor
- ← EarlierCVE-2023-36359Jun 22, 2023 · TP-Link TL-WR940N V4, TL-WR841N V8/V10, TL-WR940N V2/V3 and TL-WR941ND V5/V6 were discovered to contain a buffer overflow in the component /30Monitor
- Later →CVE-2025-6151Jun 16, 2025 · TP-Link TL-WR940N, TL-WR841N WanSlaacCfgRpm.htm buffer overflow33Monitor
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
Proof of concept available
A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.
Evidence
- Proof-of-concept repository on GitHub ×1
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Proof-of-concept repository on GitHub | stars:0 | 2026-06-06 |
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.
- Published
- First PoC+512 d
- TodayOct 21, 2026+650 d
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 researchersFinders, 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
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Someone on the same network segment can trigger it.
- A low-privileged account is enough.
- 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
- Adjacent
- Attack complexity
- Low
- Privileges required
- Low
- 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:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
nvd-secondary
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 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
char buf[256];memcpy(buf, pkt->data, pkt->len);Fixed
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.
Attack patterns (CAPEC)
- Buffer Overflow via Environment VariablesCAPEC-10likelihood: High · High
- Overflow BuffersCAPEC-100likelihood: High · Very High
- Client-side Injection-induced Buffer OverflowCAPEC-14likelihood: Medium · High
- Filter Failure through Buffer OverflowCAPEC-24likelihood: High · High
- MIME ConversionCAPEC-42likelihood: High · High
- Overflow Binary Resource FileCAPEC-44likelihood: High · Very High
- Buffer Overflow via Symbolic LinksCAPEC-45likelihood: High · High
- Overflow Variables and TagsCAPEC-46likelihood: High · High
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.