CVE-2026-19565Network attack vector

Authentication bypass via predictable session keys

Published Aug 23, 2026 · Updated Aug 23, 2026

Authentication bypass in Paul M. Hirsch Apache-AppSamurai 1.01 and earlier allows remote attackers to recover victim session cookies. CreateSessionAuthKey performs five SHA-256 rounds over fresh microsecond clock readings, the prior digest, and a small-range worker process ID. Exploitation requires the victim session's creation second and worker process ID, plus online testing of candidates against a server that holds the configured key.

CVSS severityUnavailable
Unscored
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Paul M. Hirsch Apache-AppSamurai 1.01 and earlier allows remote attackers to recover victim session cookies. CreateSessionAuthKey performs five SHA-256 rounds over fresh microsecond clock readings, the prior digest, and a small-range worker process ID. Exploitation requires the victim session's creation second and worker process ID, plus online testing of candidates against a server that holds the configured key.

The record

CVE
CVE-2026-19565
Published
Aug 23, 2026
Updated
Aug 23, 2026
Vendor
Paul M. Hirsch
Product
Apache-AppSamurai
Classifications
CWE-341, CAPEC-115, CAPEC-59, T1550.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 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?

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  1. Affected versionversion=0 <=1.01

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Paul M. Hirsch · Apache-AppSamuraiversion=0 <=1.01

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-341Predictable from Observable State
CAPEC-115Authentication Bypass
CAPEC-59Session Credential Falsification through Prediction
T1550.004Web Session Cookie

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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