Evidence used
- No CISA KEV confirmation is currently recorded.
- EPSS is 0.44% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-76651High confidence
Pre-Authentication Multipart Boundary Buffer Overflow in HTTP Service in TP-Link TL-WR841N
TP-Link System Inc. · TL-WR841N v14
5.3MediumCVSS 4.0
Scheduled
Patch availableMedium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityMedium→Operational priority:Medium, unchanged from published severity.unchanged
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict local access and enforce least privilege on affected hosts.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs TP-Link System Inc. TL-WR841N v14 and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.
Patch available01
What, why and how
A buffer overflow vulnerability exists in the embedded HTTP service in TL-WR841N v14 when processing multipart/form-data requests. Insufficient validation of an attacker-controlled boundary parameter may allow a remote unauthenticated attacker to submit a crafted request that corrupts memory by overwriting data beyond the bounds of an internal buffer. Successful exploitation may result in modification or corruption of process memory, potentially leading to undefined application behavior. Arbitrary code execution, information disclosure, and denial-of-service conditions have not been demonstrated.
What
A buffer overflow vulnerability exists in the embedded HTTP service in TL-WR841N v14 when processing multipart/form-data requests. Insufficient validation of an attacker-controlled boundary parameter may allow a remote unauthenticated attacker to submit a crafted request that corrupts memory by overwriting data beyond the bounds of an internal buffer. Successful exploitation may result in modification or corruption of process memory, potentially leading to undefined application behavior. Arbitrary code execution, information disclosure, and denial-of-service conditions have not been demonstrated.
Why
The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.
How
An attacker operating through an adjacent network may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.
What
A buffer overflow vulnerability exists in the embedded HTTP service in TL-WR841N v14 when processing multipart/form-data requests. Insufficient validation of an attacker-controlled boundary parameter may allow a remote unauthenticated attacker to submit a crafted request that corrupts memory by overwriting data beyond the bounds of an internal buffer. Successful exploitation may result in modification or corruption of process memory, potentially leading to undefined application behavior. Arbitrary code execution, information disclosure, and denial-of-service conditions have not been demonstrated.
Why
The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.
How
An attacker operating through an adjacent network may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- an adjacent network → Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') → execute code or commands in the affected security context
- Attack surface
- Adjacent
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Not a CVSS 4.0 base metric
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-120 ↗
CWE-120: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow'). The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:NCommon Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.
AVAdjacentAttack vector: The attacker must be on an adjacent or logically close network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATNoneAttack requirements: No additional deployment or execution condition is required.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCNoneVulnerable-system confidentiality: No direct loss is represented by this metric.VILowVulnerable-system integrity: A successful attack can cause a limited loss.VANoneVulnerable-system availability: No direct loss is represented by this metric.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.- Post-exploitation / living off the land
- After compromise, an attacker may use built-in shells, scripting engines, scheduled tasks and native network utilities for discovery, persistence or movement. This is a plausible LoTL path, not evidence that it has occurred for every attack.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Patch available
- Action
- Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
- Workaround
- No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04
Evidence and provenance
Published 28 Aug 2026 · Last source change 31 Aug 2026, 18:36 UTC · CWE-120 · Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-29
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-67937
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD not scheduled
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- ENISA EUVD mappingEUVD-2026-67937 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2026-67937"}
- Affected versionsThe structured affected or fixed version information changed.CNA ↗
- Before
- < TL-WR841N(US)_V14_4.19 Build 260820 Rel.33478; < TL-WR841N(EU)_V14_4.19 Build 260821 Rel.56588 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- After
- TL-WR841N v14: < TL-WR841N(US)_V14_4.19 Build 260820 Rel.33478, < TL-WR841N(EU)_V14_4.19 Build 260821 Rel.56588 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- Catalogue recordCVE added to the BlackTree catalogue.CNA ↗
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.