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CVE-2019-3561

31
FAUCET Score

CVE-2019-3561 is a critical vulnerability affecting all supported versions of HHVM (4.0.3, 3.30.4, and 3.27.7 and below). It stems from insufficient boundary checks in the strrpos and strripos functions, leading to out-of-bounds memory access. With a CVSS score of 9.8 (Critical), this vulnerability is remotely exploitable with low attack complexity, allowing for potential complete compromise of confidentiality, integrity, and availability. While there is no evidence of active exploitation or public exploit code, the vulnerability has garnered significant community discussion, indicating awareness and potential future interest.

Impacted Technologies

VendorProductVersion(s)CPE
<= 3.27.7CPE matchmatch criteria
cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*
>= 3.28.0, <= 3.30.4CPE matchmatch criteria
cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*
>= 4.0.0, <= 4.0.3CPE matchmatch criteria
cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*
< 3.27.8CPE match
cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

9.8CRITICAL

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.0

Exploit Intelligence

EPSS Score
1.71%
Probability of exploitation in next 30 days
EPSS Percentile
75.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-24
Model: v2026.06.15
This CVE's current EPSS score of 0.0171 is in the 63rd percentile among its peer group of 36,829 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

github.com / facebook/hhvm/commit/46003b4ab564b2abcd8470035fc324fe36aa8c75
Third Party Advisory
hhvm.com / blog/2019/04/03/hhvm-4.0.4.html
Vendor Advisory