Skip to main content

Boteraser | Website and Server Security Solutions

🛡️ CVE-2026-52747 — modsecurity

🟠 CVSS 8.0 — High ⚠️ Exploit Public CWE-180 OSV
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

ModSecurity: Multipart form-data parser silently strips embedded line breaks from form-field values, enabling request-body inspection bypass

ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Prior to 3.0.16, the multipart/form-data request body parser in libmodsecurity silently removes embedded line breaks from non-file form-field values before exporting them to ARGS and ARGS_POST because src/request_body_processor/multipart.cc overwrites reserved bytes in m_reserve instead of appending the current buffer. This creates a parser differential between ModSecurity and backend applications that preserve line breaks in form fields, allowing rules that inspect ARGS or ARGS_POST to miss payloads whose dangerous syntax depends on a line break. This issue is fixed in version 3.0.16.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is changed, meaning a successful attack can affect components beyond the vulnerable one. Rated impact: confidentiality none, integrity high, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Changed — a successful attack reaches components beyond the vulnerable one.
  • Confidentiality impact: None.
  • Integrity impact: High — total loss, or loss the attacker controls.
  • Availability impact: None.

Weakness class

CVE-2026-52747 is classified as CWE-180: Incorrect Behavior Order: Validate Before Canonicalize. The product validates input before it is canonicalized, which prevents the product from detecting data that becomes invalid after the canonicalization step.

Affected software

CVE-2026-52747 is recorded against 2 packages.

  • modsecurity
  • modsecurity2

Timeline and source

Published on 15 July 2026 and last revised on 21 July 2026. A public exploit is known to exist, which raises the urgency of patching considerably. A vendor advisory or fix has been published. Record sourced from OSV.

References

github.com (Web)
github.com (Web)
github.com (Web)
nvd.nist.gov (Web)

Other advisories for this package

modsecurity has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-180: Incorrect Behavior Order: Validate Before Canonicalize) in other software:

Details

Severity HIGH
CVSS Score 8.0
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
CWE CWE-180
Public Exploit ⚠️ Yes
Source OSV
Published 2026-07-15
Updated 2026-08-20
Modified 2026-07-21

Affected Packages

Software From version Fixed in
modsecurity — —
modsecurity2 — —

Similar Threats

Exploit Protection

Are you running modsecurity?

CVE-2026-52747 carries CVSS 8.0 High rating and a public exploit already exists. BotEraser checks your installation against this and other known CVE records, and blocks IPs associated with exploit activity.

Check My Site For CVE-2026-52747 →

No credit card required  ·  Results in minutes

ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

Browse related advisories

All advisoriesCVECVE 2026
✓