CVE-2021-22570Network attack vector

Compiler crash via null-character proto symbol

Published Jan 26, 2022 · Updated Apr 21, 2025

Null pointer dereference in Google Protocol Buffers before 3.15.0 allows attackers to crash protoc with a null-containing proto symbol. The symbol parser misclassifies the input, leaves the associated file pointer null, and dereferences it while formatting an error through the file-name accessor. The attacker must cause an affected C++ compiler invocation to process the crafted symbol; the bounded consequence is termination of that compiler process.

CVSS severity5.5
Medium
EPSS probability2.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Null pointer dereference in Google Protocol Buffers before 3.15.0 allows attackers to crash protoc with a null-containing proto symbol. The symbol parser misclassifies the input, leaves the associated file pointer null, and dereferences it while formatting an error through the file-name accessor. The attacker must cause an affected C++ compiler invocation to process the crafted symbol; the bounded consequence is termination of that compiler process.

The record

CVE
CVE-2021-22570
Published
Jan 26, 2022
Updated
Apr 21, 2025
Vendor
Google
Product
Protocol Buffers
Classifications
CWE-476, T1499
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 26, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=unspecified <3.15.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Google · Protocol Buffersversion=unspecified <3.15.0

Published CVSS scores

6.5Google LLCCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
2.1NIST NVDAV:L/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo