CVE-2026-23836Network attack vector

Authenticated PHP code execution via formula comment injection

Published Jan 19, 2026 · Updated Jan 19, 2026

Eval injection in HotCRP 3.1 allows remote authenticated users to execute arbitrary PHP code through a crafted formula expression. In src/formula.php, _compile_function and support_combiner interpolated the original formula text into PHP comments inside strings passed to eval without neutralizing the ?> closing tag. Any low-privileged account able to submit a formula can close the generated PHP context and run code with the web application privileges, exposing server data and application integrity.

CVSS severity9.9
Critical
EPSS probability0.45%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Eval injection in HotCRP 3.1 allows remote authenticated users to execute arbitrary PHP code through a crafted formula expression. In src/formula.php, _compile_function and support_combiner interpolated the original formula text into PHP comments inside strings passed to eval without neutralizing the ?> closing tag. Any low-privileged account able to submit a formula can close the generated PHP context and run code with the web application privileges, exposing server data and application integrity.

The record

CVE
CVE-2026-23836
Published
Jan 19, 2026
Updated
Jan 19, 2026
Vendor
Eddie Kohler
Product
HotCRP
Classifications
CWE-95, CWE-20, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 19, 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== 3.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Eddie Kohler · HotCRPversion== 3.1

Published CVSS scores

9.9GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-95Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')
CWE-20Improper Input Validation
T1190Exploit Public-Facing Application

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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