CVE-2023-28320Public exploitNetwork attack vector

Application crash via unlocked DNS timeout buffer

Published May 26, 2023 · Updated Jan 15, 2025

Race condition in libcurl 7.9.8 through 8.0.1 allows remote attackers to crash multithreaded applications during DNS timeouts. Curl_resolv_timeout stores each sigsetjmp return context in the global curl_jmpenv buffer without a mutex, so concurrent threads overwrite shared jump state. The flaw requires a build with the synchronous resolver plus alarm and siglongjmp support; affected processes can crash or otherwise misbehave.

CVSS severity5.9
Medium
EPSS probability2.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in libcurl 7.9.8 through 8.0.1 allows remote attackers to crash multithreaded applications during DNS timeouts. Curl_resolv_timeout stores each sigsetjmp return context in the global curl_jmpenv buffer without a mutex, so concurrent threads overwrite shared jump state. The flaw requires a build with the synchronous resolver plus alarm and siglongjmp support; affected processes can crash or otherwise misbehave.

The record

CVE
CVE-2023-28320
Published
May 26, 2023
Updated
Jan 15, 2025
Vendor
curl
Product
curl
Classifications
CWE-662, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 26, 2023CVE publishedPublication date reported by the CVE source.
  2. Jan 15, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Fixed in 8.1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

curl · curlversion=Fixed in 8.1.0

Published CVSS scores

5.9CISA-ADPCVSS:3.1/AV:N/AC:H/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 exploitPublished

Weakness, pattern, technique

CWE-662Improper Synchronization
T1499.004Application or System Exploitation

Public exploit references

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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