CVE-2020-1898Network attack vector

Service crash via unbounded nested deserialization

Published Mar 11, 2021 · Updated Aug 4, 2024

Uncontrolled recursion in Meta Platforms HHVM before 4.32.3 allows remote attackers to crash the runtime via nested serialized data. The fb_unserialize and fb_compact_unserialize routines recursively decode nested containers without tracking depth, so crafted input exhausts the process stack. The flaw also affects 4.33.0 through 4.56.0 and versions 4.57.0, 4.58.0, 4.58.1, 4.59.0, 4.60.0, 4.61.0, and 4.62.0; application code must pass attacker-controlled serialized data to either routine.

CVSS severity7.5
High
EPSS probability1.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled recursion in Meta Platforms HHVM before 4.32.3 allows remote attackers to crash the runtime via nested serialized data. The fb_unserialize and fb_compact_unserialize routines recursively decode nested containers without tracking depth, so crafted input exhausts the process stack. The flaw also affects 4.33.0 through 4.56.0 and versions 4.57.0, 4.58.0, 4.58.1, 4.59.0, 4.60.0, 4.61.0, and 4.62.0; application code must pass attacker-controlled serialized data to either routine.

The record

CVE
CVE-2020-1898
Published
Mar 11, 2021
Updated
Aug 4, 2024
Vendor
Meta Platforms, Inc.
Product
HHVM
Classifications
CWE-674, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 11, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.33.0 <unspecified
  2. Affected versionversion=4.57.0
  3. Affected versionversion=4.58.0 <unspecified
  4. Affected versionversion=4.59.0
  5. Affected versionversion=4.60.0
  6. Affected versionversion=4.61.0
  7. Affected versionversion=4.62.0
  8. Affected versionversion=unspecified <4.32.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Meta Platforms, Inc. · HHVMversion=4.33.0 <unspecified; version=4.57.0; version=4.58.0 <unspecified; version=4.59.0; version=4.60.0; version=4.61.0; version=4.62.0; version=unspecified <4.32.3

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-674Uncontrolled Recursion
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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