CVE-2023-25193Network attack vector

Denial of service via repeated backward glyph scans

Published Feb 4, 2023 · Updated Mar 25, 2025

Denial of service in GPOS mark attachment in HarfBuzz 6.0.0 and earlier allows remote attackers to exhaust CPU via consecutive marks. GPOS mark attachment repeatedly scans backward over prior marks for each new mark instead of retaining the last eligible base glyph, producing quadratic work. Shaping a run of attacker-controlled consecutive marks is sufficient to consume CPU and interrupt the hosting application.

CVSS severity7.5
High
EPSS probability1.81%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in GPOS mark attachment in HarfBuzz 6.0.0 and earlier allows remote attackers to exhaust CPU via consecutive marks. GPOS mark attachment repeatedly scans backward over prior marks for each new mark instead of retaining the last eligible base glyph, producing quadratic work. Shaping a run of attacker-controlled consecutive marks is sufficient to consume CPU and interrupt the hosting application.

The record

CVE
CVE-2023-25193
Published
Feb 4, 2023
Updated
Mar 25, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-770, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 4, 2023CVE publishedPublication date reported by the CVE source.
  2. Mar 25, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5NIST NVDCVSS: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
T1499.004Application or System Exploitation 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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