CVE-2024-26134Public exploitNetwork attack vector

Service crash via long ASCII text decoding

Published Feb 19, 2024 · Updated Feb 13, 2025

Buffer overflow in cbor2 5.5.1 through 5.6.1 allows remote attackers to crash services by supplying CBOR with a long ASCII string. The C decoder's long-text path triggers a CPython error while decoding all-ASCII content, corrupting allocator state instead of returning the string. Exploitation requires an application to pass attacker-controlled CBOR to the affected C decoder; the demonstrated consequence is process termination.

CVSS severity7.5
High
EPSS probability1.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in cbor2 5.5.1 through 5.6.1 allows remote attackers to crash services by supplying CBOR with a long ASCII string. The C decoder's long-text path triggers a CPython error while decoding all-ASCII content, corrupting allocator state instead of returning the string. Exploitation requires an application to pass attacker-controlled CBOR to the affected C decoder; the demonstrated consequence is process termination.

The record

CVE
CVE-2024-26134
Published
Feb 19, 2024
Updated
Feb 13, 2025
Vendor
Alex Grönholm
Product
cbor2
Classifications
CWE-120, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 19, 2024CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2025Record 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=>= 5.5.1, < 5.6.2
  2. Affected versionversion=5.5.1 <5.6.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Alex Grönholm · cbor2version=>= 5.5.1, < 5.6.2; version=5.5.1 <5.6.2

Published CVSS scores

7.5GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1499Endpoint Denial of Service

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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