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CVE-2020-1899

19
FAUCET Score

CVE-2020-1899 is a high-severity vulnerability affecting HHVM versions prior to 4.32.3 and various versions between 4.33.0 and 4.62.0. It stems from the unserialize() function's improper handling of the "S" type code, allowing arbitrary memory addresses to be accessed as static StringData objects. With a CVSS score of 7.5 (High), this vulnerability can be exploited remotely with low attack complexity, potentially leading to high confidentiality impact. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
< 4.32.3CPE matchmatch criteria
cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*
>= 4.33.0, < 4.56.1CPE matchmatch criteria
cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*
4.57.0CPE matchmatch criteria
cpe:2.3:a:facebook:hhvm:4.57.0:*:*:*:*:*:*:*
4.58.0CPE matchmatch criteria
cpe:2.3:a:facebook:hhvm:4.58.0:*:*:*:*:*:*:*
4.58.1CPE matchmatch criteria
cpe:2.3:a:facebook:hhvm:4.58.1:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.22%
Probability of exploitation in next 30 days
EPSS Percentile
65.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0122 is in the 45th percentile among its peer group of 51,553 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

References

github.com / facebook/hhvm/commit/1107228a5128d3ca1c4add8ac1635d933cbbe2e9
PatchThird Party Advisory
hhvm.com / blog/2020/06/30/security-update.html
Vendor Advisory