CVE-2019-3570 [Critical] | Information Disclosure in Hiphop Virtual Machine

Call to the scrypt_enc() function in HHVM can lead to heap corruption by using specifically crafted parameters (N, r and p). This happens if the parameters are configurable by an attacker for instance by providing the output of scrypt_enc() in a context where Hack/PHP code would attempt to verify it by re-running scrypt_enc() with the same parameters. This could result in information disclosure, memory being overwriten or crashes of the HHVM process. This issue affects versions 4.3.0, 4.4.0, 4.5.0, 4.6.0, 4.7.0, 4.8.0, versions 3.30.5 and below, and all versions in the 4.0, 4.1, and 4.2 series.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.61%	1.68%	+1.07%
2	2025-03-30	1.17%	0.61%	-0.57%
3	2025-03-29	—	1.17%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.61%

1.68%

+1.07%

2025-03-30

1.17%

0.61%

-0.57%

2025-03-29

—

1.17%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
9.8	3.1	CRITICAL	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	5.9	[email protected]
7.5	2.0	HIGH	`AV:N/AC:L/Au:N/C:P/I:P/A:P` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:N) No authentication is required. Confidentiality impact (C:P) Partial confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:P) Partial availability impact.	10.0	6.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

9.8

3.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

3.9

5.9

[email protected]

7.5

2.0

HIGH

AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:L): Exploitation conditions are straightforward and predictable.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:P): Partial confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:P): Partial availability impact.

10.0

6.4

[email protected]

OS Trackers for CVE-2019-3570

vendor	priority	summary	link
`ubuntu`	medium	CVE-2019-3570 medium priority: Ubuntu including 1 source packages (hhvm), 19 status rows across 19 suites (bionic, cosmic, disco, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 16, needs-triage 3.	https://ubuntu.com/security/CVE-2019-3570

Affected software / configurations for CVE-2019-3570

Vendor	Product	Version	Raw CPE
facebook	hiphop_virtual_machine	<= 3.30.5	cpe:2.3:a:facebook:hiphop_virtual_machine::::::::
facebook	hiphop_virtual_machine	>= 4.0.0, <= 4.0.4	cpe:2.3:a:facebook:hiphop_virtual_machine::::::::
facebook	hiphop_virtual_machine	4.1.0	cpe:2.3:a:facebook:hiphop_virtual_machine:4.1.0:::::::*
facebook	hiphop_virtual_machine	4.2.0	cpe:2.3:a:facebook:hiphop_virtual_machine:4.2.0:::::::*
facebook	hiphop_virtual_machine	4.3.0	cpe:2.3:a:facebook:hiphop_virtual_machine:4.3.0:::::::*
facebook	hiphop_virtual_machine	4.4.0	cpe:2.3:a:facebook:hiphop_virtual_machine:4.4.0:::::::*
facebook	hiphop_virtual_machine	4.5.0	cpe:2.3:a:facebook:hiphop_virtual_machine:4.5.0:::::::*
facebook	hiphop_virtual_machine	4.6.0	cpe:2.3:a:facebook:hiphop_virtual_machine:4.6.0:::::::*
facebook	hiphop_virtual_machine	4.7.0	cpe:2.3:a:facebook:hiphop_virtual_machine:4.7.0:::::::*
facebook	hiphop_virtual_machine	4.8.0	cpe:2.3:a:facebook:hiphop_virtual_machine:4.8.0:::::::*

References for CVE-2019-3570

URL	Tags
https://github.com/facebook/hhvm/commit/cc331e4349e91706a673e2a09f1f2ea5bbb33815	Patch Third Party Advisory
https://hhvm.com/blog/2019/06/10/hhvm-4.9.0.html	Release Notes Vendor Advisory

URL

CVE-2019-3570

Exploit prediction scoring system (EPSS) score for CVE-2019-3570

Common vulnerability scoring system (CVSS) metrics for CVE-2019-3570

Weakness enumeration for CVE-2019-3570

OS Trackers for CVE-2019-3570

Affected software / configurations for CVE-2019-3570

References for CVE-2019-3570