CVE-2021-21855Public exploitNetwork attack vector

Memory corruption via overflowing sdp atom length

Published Aug 18, 2021 · Updated Aug 3, 2024

Integer overflow in GPAC 1.0.1 MPEG-4 decoding allows context-dependent attackers to corrupt memory via a crafted video file. In sdp_box_read, the 64-bit sdp atom size is truncated to 32 bits, incremented into a zero-sized allocation, then reused for a large copy. Opening the crafted file is required; the out-of-bounds write can crash the process or execute code in the library's context.

CVSS severity8.8
High
EPSS probability1.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in GPAC 1.0.1 MPEG-4 decoding allows context-dependent attackers to corrupt memory via a crafted video file. In sdp_box_read, the 64-bit sdp atom size is truncated to 32 bits, incremented into a zero-sized allocation, then reused for a large copy. Opening the crafted file is required; the out-of-bounds write can crash the process or execute code in the library's context.

The record

CVE
CVE-2021-21855
Published
Aug 18, 2021
Updated
Aug 3, 2024
Vendor
GPAC Project
Product
GPAC
Classifications
CWE-680, T1204.002, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 18, 2021CVE 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?

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

  1. Affected versionversion=GPAC Project Advanced Content commit a8a8d412dabcb129e695c3e7d861fcc81f608304, GPAC Project Advanced Content v1.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

GPAC Project · GPACversion=GPAC Project Advanced Content commit a8a8d412dabcb129e695c3e7d861fcc81f608304, GPAC Project Advanced Content v1.0.1

Published CVSS scores

8.8Cisco TalosCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

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 exploitPublished

Weakness, pattern, technique

CWE-680Integer Overflow to Buffer Overflow
T1204.002Malicious File
T1203Exploitation for Client Execution

Public exploit references

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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