CVE-2026-88355

Process termination via undersized expression-node allocation

Published Sep 24, 2026 · Updated Sep 24, 2026

Incorrect buffer-size calculation in tinyexpr commit 4a7456e allows attackers to terminate UBSan-instrumented processes via parsed expressions. In new_expr, the allocation formula removes one pointer slot for arity-zero nodes, then accesses the allocation as a complete te_expr object. The affected path covers constants, variables, and zero-argument functions; uninstrumented behavior is undefined, while UBSan instrumentation makes termination deterministic.

CVSS severityUnavailable
Unscored
EPSS probability0.34%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect buffer-size calculation in tinyexpr commit 4a7456e allows attackers to terminate UBSan-instrumented processes via parsed expressions. In new_expr, the allocation formula removes one pointer slot for arity-zero nodes, then accesses the allocation as a complete te_expr object. The affected path covers constants, variables, and zero-argument functions; uninstrumented behavior is undefined, while UBSan instrumentation makes termination deterministic.

The record

CVE
CVE-2026-88355
Published
Sep 24, 2026
Updated
Sep 24, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1499
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Sep 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 24, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

No CVSS assessment is available in this record.

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.

Activity data is delayed. The latest report is Sep 28, 2026.

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No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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