CVE-2026-55971Network attack vector

Remote code execution via ZLIB copy-back overflow

Published Jul 27, 2026 · Updated Jul 27, 2026

Heap-based buffer overflow in Apache Thrift C++ bindings before 0.24.0 allows remote attackers to corrupt memory via ZLIB-compressed frames. The THeaderTransport::untransform() method inflates data into a transform buffer, then copies the larger output into the smaller frame receive buffer without checking its capacity. Reachability requires a C++ client or server using Header transport with ZLIB compression; successful exploitation can crash the process or execute code.

CVSS severity9.3
Critical
EPSS probability0.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in Apache Thrift C++ bindings before 0.24.0 allows remote attackers to corrupt memory via ZLIB-compressed frames. The THeaderTransport::untransform() method inflates data into a transform buffer, then copies the larger output into the smaller frame receive buffer without checking its capacity. Reachability requires a C++ client or server using Header transport with ZLIB compression; successful exploitation can crash the process or execute code.

The record

CVE
CVE-2026-55971
Published
Jul 27, 2026
Updated
Jul 27, 2026
Vendor
The Apache Software Foundation
Product
Apache Thrift
Classifications
CWE-122, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 27, 2026Record 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=0 <0.24.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Thriftversion=0 <0.24.0

Published CVSS scores

8.4Red HatCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.3Apache Software FoundationCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-122Heap-based Buffer Overflow
T1190Exploit Public-Facing Application

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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