CVE-2021-33499Network attack vector

Remote service interruption via unvalidated H.264 input

Published Jan 15, 2022 · Updated Aug 3, 2024

Improper H.264 input validation in Pexip Infinity before 26 allows remote attackers to interrupt conferencing service over the network. The H.264 media-processing path accepts malformed codec input without required validation, triggering the denial-of-service condition. No authentication or user interaction is required, and public sources do not identify the exact parser or whether interruption results from a crash or hang.

CVSS severity7.5
High
EPSS probability1.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper H.264 input validation in Pexip Infinity before 26 allows remote attackers to interrupt conferencing service over the network. The H.264 media-processing path accepts malformed codec input without required validation, triggering the denial-of-service condition. No authentication or user interaction is required, and public sources do not identify the exact parser or whether interruption results from a crash or hang.

The record

CVE
CVE-2021-33499
Published
Jan 15, 2022
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-20, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 15, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

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

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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-20Improper Input Validation
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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