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CVE Record

CVE-2026-5081: Apache::Session::Generate::ModUniqueId versions from 1.54 through 1.94 for Perl session ids are insecure

Apache::Session::Generate::ModUniqueId versions from 1.54 through 1.94 for Perl session ids are insecure. Apache::Session::Generate::ModUniqueId (added in version 1.54) uses the value of the UNIQUE_ID environment variable for the session id. The UNIQUE_ID variable is set by the Apache mod_unique_id plugin, which generates unique ids for the request. The id is based on the IPv4 address, the process id, the epoch time, a 16-bit counter and a thread index, with no obfuscation. The server IP is often available to the public, and if not available, can be guessed from previous session ids being issued. The process ids may also be guessed from previous session ids. The timestamp is easily guessed (and leaked in the HTTP Date response header). The purpose of mod_unique_id is to assign a unique id to requests so that events can be correlated in different logs. The id is not designed, nor is it suitable for security purposes.

CriticalCVSS 9.1Not KEV-listedUpdated
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Glexia's TakeAutomated analysiscritical

Security readout for executives and security teams

Plain-English summary

This flaw affects Perl applications that use Apache::Session::Generate::ModUniqueId for session IDs. Those IDs are built from predictable request metadata rather than security-grade randomness, so an attacker may be able to guess valid sessions and impersonate users.

Executive priority

Treat this as urgent where affected Perl applications protect customer, admin, or employee sessions. The main business risk is account takeover through predictable sessions, not server downtime.

Technical view

Apache::Session::Generate::ModUniqueId versions 1.54 through 1.94 use Apache mod_unique_id UNIQUE_ID values as session IDs. The source data includes IP address, process ID, epoch time, counter, and thread index, with no obfuscation. The CVE maps this to predictable random number generation weaknesses.

Likely exposure

Exposure is likely limited to Perl applications using Apache-Session with Apache::Session::Generate::ModUniqueId for authentication or security-sensitive session identifiers. General use of Apache mod_unique_id for log correlation is not the issue described.

Exploitation context

The source bundle does not state active exploitation, and KEV is false. Risk remains high because the attack is network-reachable, requires no privileges or user interaction, and targets session confidentiality and integrity through predictable IDs.

Researcher notes

Do not conflate mod_unique_id’s log-correlation purpose with session security. The cited Apache documentation says UNIQUE_ID is for request uniqueness, while the CVE explains its components are guessable or leaked. Evidence does not include exploit-in-the-wild claims.

Mitigation direction

  • Inventory Perl applications using Apache::Session::Generate::ModUniqueId.
  • Stop using ModUniqueId-generated values for security-sensitive session IDs.
  • Check Apache-Session or distributor guidance for a fixed version or migration path.
  • Evaluate a cryptographic random session ID generator, such as documented Apache::Session random generation.
  • Prioritize externally exposed authentication workflows first.

Validation and detection

  • Search dependencies and code for Apache::Session::Generate::ModUniqueId.
  • Confirm deployed Apache-Session versions are not 1.54 through 1.94 when using this generator.
  • Review session configuration for any use of UNIQUE_ID as the session identifier.
  • Test that new sessions are generated with security-grade randomness after remediation.
  • Check Red Hat or vendor advisories for package-specific status.
Prepared
Confidence
high
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-340: Exact CWE lookup

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cwe · low confidence lookup

CWE-341: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cve · low confidence lookup

CVE-2026-5081 mapping review

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Vulnerability profileCVE Program record
Severity
Critical
CVSS
9.1 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
3ADP providers
6Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
9.1CVSS 3.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N3.95.2CISA-ADP
8.2CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N3.94.2redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

9.1Critical
CVSS 3.1 vector shape for CVE-2026-5081Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
cvssV3_1other:ssvc
CVECVE Program Container
redhat-SADPApache::Session::Generate::ModUniqueId: Perl: mod_unique_id: Apache HTTP Server: Apache::Session::Generate::ModUniqueId: Session ID predictability allows unauthorized access
other:Red Hat severity ratingcvssV3_1
  • 2026-05-06T13:08:16.703Z: Reported to Red Hat.
  • 2026-05-06T12:16:38.452Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
CHORNYApache::Session::Generate::ModUniqueIdApache-Session, 1.54unaffected
Weakness

CWE details

CWE-340CWE-341

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-340 · source CWE mapping

Generation of Predictable Numbers or Identifiers

Generation of Predictable Numbers or Identifiers represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-341 · source CWE mapping

Predictable from Observable State

Predictable from Observable State represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs