CVE-2026-5081Network attack vector

Session hijacking via predictable request identifiers

Published May 6, 2026 · Updated May 6, 2026

Predictable session identifiers in Apache::Session::Generate::ModUniqueId 1.54 through 1.94 allow remote attackers to hijack sessions. The generate_id routine copies Apache mod_unique_id's UNIQUE_ID environment value directly into the session identifier despite its observable timestamp and request-state components. Exploitation requires a consuming application to use this generator for authentication or restricted-data access; a predicted identifier grants the corresponding session's access.

CVSS severity9.1
Critical
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Predictable session identifiers in Apache::Session::Generate::ModUniqueId 1.54 through 1.94 allow remote attackers to hijack sessions. The generate_id routine copies Apache mod_unique_id's UNIQUE_ID environment value directly into the session identifier despite its observable timestamp and request-state components. Exploitation requires a consuming application to use this generator for authentication or restricted-data access; a predicted identifier grants the corresponding session's access.

The record

CVE
CVE-2026-5081
Published
May 6, 2026
Updated
May 6, 2026
Vendor
Alexandr Ciornii
Product
Apache::Session::Generate::ModUniqueId
Classifications
CWE-340, CWE-341, T1550.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 6, 2026CVE publishedPublication date reported by the CVE source.
  2. May 6, 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=1.54 <=1.94

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Alexandr Ciornii · Apache::Session::Generate::ModUniqueIdversion=1.54 <=1.94

Published CVSS scores

9.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
8.2Red HatCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-340Generation of Predictable Numbers or Identifiers
CWE-341Predictable from Observable State
T1550.004Use Alternate Authentication Material: Web Session Cookie

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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