CVE-2026-52747: ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx

Q: How do I fix CVE-2026-52747?

modsecurity: upgrade to 3.0.16. Exact commands for each OS are on this page.

Q: Is CVE-2026-52747 being exploited?

CVE-2026-52747 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-52747 affect?

CVE-2026-52747 affects modsecurity. Severity is high (CVSS 8.6). 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-fil

Q: How urgent is CVE-2026-52747?

Priority 55/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

This week

HIGH 8.6REMOTEWATCHLISTUPGRADE

CVE-2026-52747 is a high-severity flaw (CVSS 8.6) affecting modsecurity. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 par

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	8.6 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 59%)
CISA exploited list	No
Weakness	CWE-180
Published	2026-07-10
Last modified	2026-10-25

Publisher (CNA): GitHub, Inc. · Vendor: owasp

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-10 22:16 UTCPublished CVE record published
2026-10-25 15:10 UTCUpdated Record last modified

owasp modsecurity UPGRADE

Affected: < 3.0.16

Fixed in: 3.0.16

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy modsecurity || rpm -q modsecurity || modsecurity --version

2. UPGRADE to 3.0.16 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade modsecurity

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade modsecurity

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Exact fixes by distribution

Fedora ELN · nginx-mod-headers-more · FIXED · 0.41-1.eln159 · FEDORA-2026-31f55f396a · source

sudo dnf upgrade --advisory=FEDORA-2026-31f55f396a

Fedora 46 · erlang-hex_core · FIXED · 0.21.1-1.fc46 · FEDORA-2026-f3389199ff · source

sudo dnf upgrade --advisory=FEDORA-2026-f3389199ff

Debian 12 · modsecurity · NO FIX YET

Debian 13 · modsecurity · NO FIX YET

RHEL 7 · mod_security · DEFERRED

RHEL 8 · mod_security · DEFERRED

RHEL 9 · mod_security · DEFERRED

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-rcw9-2f5r-7p88

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-52747?

modsecurity: upgrade to 3.0.16. Exact commands for each OS are on this page.

Is CVE-2026-52747 being exploited?

CVE-2026-52747 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-52747 affect?

CVE-2026-52747 affects modsecurity. Severity is high (CVSS 8.6). 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-fil

How urgent is CVE-2026-52747?

Priority 55/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

nginx vulnerabilities

Related CVEs

CVE-2026-52761 MEDIUM 5.8 UPGRADE ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx

References

← Back to latest CVEs