CVE-2026-77358Public exploit

Service crash via freed TLS session reuse

Published Aug 27, 2026 · Updated Aug 27, 2026

Use-after-free in cpp-httplib 0.33.0 through 0.50.0 allows attackers to crash clients during secure WebSocket teardown. WebSocketClient::shutdown_and_close frees tls_session_ before ws_->close sends a close frame through SSLSocketStream, whose raw session pointer then reads from and writes to freed memory. When a TLS-enabled wss:// connection remains open during destruction or reconnection without an explicit close, the client process can terminate; code execution has not been demonstrated.

CVSS severityUnavailable
Unscored
EPSS probability0.29%
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 cpp-httplib 0.33.0 through 0.50.0 allows attackers to crash clients during secure WebSocket teardown. WebSocketClient::shutdown_and_close frees tls_session_ before ws_->close sends a close frame through SSLSocketStream, whose raw session pointer then reads from and writes to freed memory. When a TLS-enabled wss:// connection remains open during destruction or reconnection without an explicit close, the client process can terminate; code execution has not been demonstrated.

The record

CVE
CVE-2026-77358
Published
Aug 27, 2026
Updated
Aug 27, 2026
Vendor
Yuji Hirose
Product
cpp-httplib
Classifications
CWE-416, T1499
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Aug 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 27, 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=>= 0.33.0, < 0.50.

What conditions does exploitation require?

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

What is affected?

Yuji Hirose · cpp-httplibversion=>= 0.33.0, < 0.50.

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.

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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)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-416Use After Free
T1499Endpoint Denial of Service

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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