Cyber Resilience

CVE-2025-6121

Memory Safety in Dlink Dir-632 Firmware 103b08

Public PoCMemory Safety
Published
16 June 2025
Modified
17 June 2026
Patch / advisory
View advisory
CVSS Score v4 8.9
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.019 78th percentile
Risk Priority 48 floored blend · peak EPSS

Summary

CVE-2025-6121 is a high-severity Improper Restriction of Operations within the Bounds of a Memory Buffer (CWE-119) vulnerability in Dlink Dir-632 Firmware. Its CVSS base score is 8.9 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 22% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

A critical stack-based buffer overflow vulnerability, tracked as CVE-2025-6121 and assigned CWE-119 and CWE-121, exists in the get_pure_content function of the HTTP POST Request Handler on the D-Link DIR-632 running firmware FW103B08. The flaw is triggered by manipulation of the Content-Length argument supplied in an HTTP POST request and carries a CVSS 4.0 score of 8.9.

An unauthenticated remote attacker can send a crafted POST request to trigger the overflow, resulting in arbitrary code execution or a denial-of-service condition on the device. Public proof-of-concept code has been released, confirming that exploitation is possible over the network without any user interaction or credentials.

The affected router model is no longer supported by D-Link, and the supplied references contain only disclosure and exploit details rather than vendor patches or mitigation guidance. The associated EPSS score has remained flat at 0.0129 with no material increase since publication.

EU & UK References

Vulnerability Data

A vulnerability, which was classified as critical, has been found in D-Link DIR-632 FW103B08. Affected by this issue is the function get_pure_content of the component HTTP POST Request Handler. The manipulation of the argument Content-Length leads to stack-based buffer overflow.…

more

The attack may be launched remotely. The exploit has been disclosed to the public and may be used. This vulnerability only affects products that are no longer supported by the maintainer.

CWE(s)
CWE-119CWE-121

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
T1055 Process Injection Stealth
Adversaries may inject code into processes in order to evade process-based defenses as well as possibly elevate privileges.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-5912Same product: Dlink Dir-632
CVE-2025-5969Same product: Dlink Dir-632
CVE-2026-7851Same vendor: Dlink
CVE-2026-2882Same vendor: Dlink
CVE-2026-2925Same vendor: Dlink
CVE-2025-7194Same vendor: Dlink
CVE-2025-6370Same vendor: Dlink
CVE-2025-6291Same vendor: Dlink
CVE-2025-7762Same vendor: Dlink
CVE-2025-8949Same vendor: Dlink

Affected Assets

dlink
dir-632 firmware
103b08

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 2 hardening rules · 2 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V17.3.2

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and analysis can discover stack-buffer overflows before deployment.

SI-10 Information Input Validation good match

Input validation directly stops untrusted data from exceeding stack buffer bounds.

SI-16 Memory Protection good match

Memory-protection mechanisms limit the ability to execute injected code after a stack overflow.

SA-8 Security and Privacy Engineering Principles partial match

Secure engineering principles require memory-safe design and coding that structurally avoids buffer-boundary violations.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices (bounds checking, safe APIs, reviews) directly prevent this class of flaw.

ID.RA-01 partial match
prevents

Vulnerability scanning and code analysis directly surface buffer-boundary flaws.

ID.RA-08 partial match
prevents

Receiving and triaging vulnerability disclosures commonly includes buffer-related reports.

PR.AT-02 partial match
prevents

Developer training on secure coding reduces introduction of memory-buffer errors.

PR.PS-02 partial match
prevents

Patching replaces vulnerable code containing buffer-boundary defects.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development catches out-of-bounds accesses before release, covering most instances of the weakness.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle mandates memory-safety practices that directly prevent buffer-boundary violations.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify memory-safety rules, but do not prescribe implementation details.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture and engineering principles include memory-safe design patterns that mitigate buffer overflows.

A.8.28 Secure coding partial match
prevents

Secure coding standards explicitly forbid unsafe buffer operations, directly eliminating CWE-119.

A.8.32 Change management none match
none

Change-management gates can enforce security reviews that catch buffer issues.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

Oracle Linux 8 (1 rule)
  • V-248594 OL 8 must implement address space layout randomization (ASLR) to protect its memory from unauthorized code execution. prevents CWE-121
Oracle Linux 9 (1 rule)
  • V-271452 OL 9 must use a Linux Security Module configured to enforce limits on system services. prevents CWE-121

References