CVE-2026-15747Network attack vector

CSRF bypass via reusable token compression oracle

Published Jul 14, 2026 · Updated Jul 14, 2026

Compression-oracle exposure in Mojolicious 4.59 through 9.47 allows remote attackers to recover session CSRF tokens via compressed responses. The _csrf_token helper caches one token for the session, and _csrf_field repeatedly embeds that stable value in a hidden csrf_token input. Exploitation requires a response that contains the token, reflects attacker-controlled input, uses gzip compression, and exposes repeated response lengths; recovered tokens pass csrf_protect validation.

CVSS severity9.1
Critical
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Compression-oracle exposure in Mojolicious 4.59 through 9.47 allows remote attackers to recover session CSRF tokens via compressed responses. The _csrf_token helper caches one token for the session, and _csrf_field repeatedly embeds that stable value in a hidden csrf_token input. Exploitation requires a response that contains the token, reflects attacker-controlled input, uses gzip compression, and exposes repeated response lengths; recovered tokens pass csrf_protect validation.

The record

CVE
CVE-2026-15747
Published
Jul 14, 2026
Updated
Jul 14, 2026
Vendor
Mojolicious
Product
Mojolicious
Classifications
CWE-204, CWE-352, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 14, 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=4.59 <9.48

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mojolicious · Mojoliciousversion=4.59 <9.48

Published CVSS scores

9.1UbuntuCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
9.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
5.9SUSECVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:N
4.8Amazon LinuxCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
5.9SUSECVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:A/VC:L/VI:H/VA:N/SC:N/SI:N/SA: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-204Observable Response Discrepancy
CWE-352Cross-Site Request Forgery (CSRF)
T1190Exploit Public-Facing Application

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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