CVE-2025-29786Network attack vector

Process crash via unbounded AST construction

Published Mar 17, 2025 · Updated Jan 23, 2026

Resource exhaustion in Expr before 1.17.0 allows remote attackers to crash a host process via an unbounded expression. The parser creates an AST node for each expression part without enforcing a node or memory budget, allowing compilation to consume available memory. Exposure requires a consuming application to accept arbitrarily long attacker-controlled expressions; bounded or validated inputs do not reach the crash condition.

CVSS severity7.5
High
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Expr before 1.17.0 allows remote attackers to crash a host process via an unbounded expression. The parser creates an AST node for each expression part without enforcing a node or memory budget, allowing compilation to consume available memory. Exposure requires a consuming application to accept arbitrarily long attacker-controlled expressions; bounded or validated inputs do not reach the crash condition.

The record

CVE
CVE-2025-29786
Published
Mar 17, 2025
Updated
Jan 23, 2026
Vendor
expr-lang
Product
Expr
Classifications
CWE-770, T1499.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 17, 2025CVE publishedPublication date reported by the CVE source.
  2. Jan 23, 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=< 1.17.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

expr-lang · Exprversion=< 1.17.0

Published CVSS scores

7.5GitHub, Inc.CVSS: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 exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.002Service Exhaustion Flood

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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