CVE-2018-6335

mediumpriority · track · 31EPSS 0.015 · 74 %ileEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

1.47% (74th) EPSS

CVSS 5 · medium

Is it mine?

9 products

Check your exposure

Who says so?

3 sources

cnnvd · enisa_euvd · nvd

EPSS · scored 2026-10-27

A Malformed h2 frame can cause 'std::out_of_range' exception when parsing priority meta data. This behavior can lead to denial-of-service. This affects all supported versions of HHVM (3.25.2, 3.24.6, and 3.21.10 and below) when using the proxygen server to handle HTTP2 requests.

cvss

Technical severity, 0–10. One row per scoring source.

7.5

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5–7.5

v2.05mediumAV:N/AC:L/Au:N/C:N/I:N/A:Pprimary · NVD / NIST USexploitability 10 · impact 2.9

v3.07.5highCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 3.9 · impact 3.6

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · ENISA EU

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondaryexploitability 3.9 · impact 3.6

v3.16.9mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: yes · Technical Impact: partialcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-20USprimaryCWE-400US

affected products (9)

Products and version ranges known to be affected.

Facebook HHVM≤ 3.25.0enisa_euvdEU
Facebook HHVM≤ 3.24.7enisa_euvdEU
Facebook HHVM≤ 3.25.3enisa_euvdEU
Facebook HHVM≤ 3.22.0enisa_euvdEU
Facebook HHVM≤ 3.21.11enisa_euvdEU
Facebook HHVMunspecified → 3.21.11enisa_euvdEU
facebook hhvm≤ 3.21.10nvdUScpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*
facebook hhvm= 3.24.6nvdUScpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*
facebook hhvm= 3.25.2nvdUScpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd nvd NVD CVE.org MITRE

published 2018-12-31modified 2026-06-17

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+25188 more

references (6)

External citations — patches, advisories, analysis.

scry

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