msgpack MessagePack up to 1.8.1 Buffer ext/msgpack/buffer.c Buffer#clear buffer overflow

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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5.3$0-$5k1.29+

Summaryinfo

A vulnerability identified as critical has been detected in msgpack MessagePack up to 1.8.1. Affected by this issue is the function MessagePack::Buffer#clear of the file ext/msgpack/buffer.c of the component Buffer. The manipulation leads to buffer overflow. This vulnerability is traded as CVE-2026-54522. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability, which was classified as critical, has been found in msgpack MessagePack up to 1.8.1. This issue affects the function MessagePack::Buffer#clear of the file ext/msgpack/buffer.c of the component Buffer. The manipulation with an unknown input leads to a buffer overflow vulnerability. Using CWE to declare the problem leads to CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

MessagePack for Ruby is an implementation of the MessagePack binary serialization format. Prior to 1.8.2, MessagePack::Buffer#clear in ext/msgpack/buffer.c leaves rmem_last, rmem_end, and rmem_owner stale after _msgpack_buffer_shift_chunk returns an rmem page to the shared pool, allowing a subsequent Buffer#write and a second MessagePack::Buffer to alias the page and disclose or corrupt cross-buffer data. This issue is fixed in version 1.8.2.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-54522 since 06/15/2026. The exploitation is known to be easy. The attack may be initiated remotely. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available.

Upgrading to version 1.8.2 eliminates this vulnerability.

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Productinfo

Vendor

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.5
VulDB Meta Temp Score: 5.3

VulDB Base Score: 5.5
VulDB Temp Score: 5.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Buffer overflow
CWE: CWE-120 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: MessagePack 1.8.2

Timelineinfo

06/15/2026 CVE reserved
07/30/2026 +45 days Advisory disclosed
07/30/2026 +0 days VulDB entry created
07/30/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-54522 (🔒)
GCVE (CVE): GCVE-0-2026-54522
GCVE (VulDB): GCVE-100-384869

Entryinfo

Created: 07/30/2026 19:20
Changes: 07/30/2026 19:20 (57)
Complete: 🔍
Cache ID: 216::103

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