CVE-2023-28319Public exploitNetwork attack vector

Heap disclosure via freed SSH fingerprint

Published May 26, 2023 · Updated Jan 15, 2025

Use-after-free in libcurl 7.81.0 through 8.0.1 allows remote attackers to expose heap data in failed SSH key-check errors. The ssh_check_fingerprint function frees fingerprint_b64 before failf formats that pointer into a mismatch error, exposing up to 186 heap bytes. The flaw requires a libssh2 build, CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256, a mismatching server key, and either verbose output or an error buffer.

CVSS severity7.5
High
EPSS probability2.49%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in libcurl 7.81.0 through 8.0.1 allows remote attackers to expose heap data in failed SSH key-check errors. The ssh_check_fingerprint function frees fingerprint_b64 before failf formats that pointer into a mismatch error, exposing up to 186 heap bytes. The flaw requires a libssh2 build, CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256, a mismatching server key, and either verbose output or an error buffer.

The record

CVE
CVE-2023-28319
Published
May 26, 2023
Updated
Jan 15, 2025
Vendor
curl
Product
curl
Classifications
CWE-416
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

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

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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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-416Use After Free

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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