How severe is CVE-2019-9553?

CVE-2019-9553 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2019-9553?

CVE-2019-9553 affects the following packages: bolt/bolt (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2019-9553?

The records we use list no patched version of bolt/bolt for CVE-2019-9553. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.

How do I detect CVE-2019-9553 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for bolt/bolt, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2019-9553 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2019-9553 actively exploited in the wild?

Yes. There are 3 known exploit references for CVE-2019-9553, including 1 documented proof-of-concept exploit on Exploit-DB and 2 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2019-9553?

CVE-2019-9553 has an EPSS (Exploit Prediction Scoring System) score of 1.8%, placing it in the 78th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2019-9553?

CVE-2019-9553 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2019-9553 published, and has it been updated?

CVE-2019-9553 was published on December 31, 2019 and was last updated on October 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘

🐘 Packagist

Not in CISA KEV

MEDIUM severity

CVE-2019-9553 — bolt

MEDIUM

CVE-2019-9553 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in bolt/bolt. 3 public exploit or proof-of-concept references are indexed, so weaponization risk is real. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.

Bolt Cross-site Scripting via the slug, teaser or title parameters

Also known asGHSA-2g23-qmmp-fvmr

Published

Dec 31, 2019

Updated

Oct 24, 2026

Affected

1 pkg

Patched

See advisory

Exploits

3 known

Exploitation data as of Nov 3, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.8%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs78th percentile — riskier than 78% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐘bolt/bolt

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

Bolt 3.6.4 has XSS via the slug, teaser, or title parameter to editcontent/pages, a related issue to CVE-2017-11128 and CVE-2018-19933.

Affected Packages

1 total

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`bolt/bolt`	all versions	No fix

Affected Products

1 product · 1 configurations

Application

boltboltcms

1 version

3.6.4

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

EDB-46495webappsphp

Bolt CMS 3.6.4 - Cross-Site Scripting

by Ismail Tasdelen · Mar 4, 2019

Exploit-DB Source

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for bolt/bolt, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
The records we use list no patched version of bolt/bolt for CVE-2019-9553. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.
Mitigate without a patch
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

Bolt 3.6.4 has XSS via the slug, teaser, or title parameter to editcontent/pages, a related issue to CVE-2017-11128 and CVE-2018-19933.

O3 Security · Impact-Aware SCA

Is CVE-2019-9553 in your dependencies?

Find it across Packagist, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

6.1/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CWE Classification

CWE-79Cross-site Scripting (XSS)

Weaponization

No Nuclei template or Metasploit module yet. 3 public proof-of-concept references are listed on this page.

OpenSSF Scorecard

Package health score

bolt

2.9/10

Code-Review5/10

Maintained0/10

Branch-ProtectionN/A

Assessed Oct 26, 2026

Timeline

First exploit

Mar 4, 2019

Disclosed

Dec 31, 2019

Last updated

Oct 24, 2026

Identifiers

CVE-2019-9553

GHSA-2g23-qmmp-fvmr

References

Advisorynvd.nist.gov · CVE 2019 9553 Packagegithub.com · bolt Evidencepacketstormsecurity.com · Bold CMS 3.6.4 Cross Site Scripting Evidenceexploit-db.com

Related vulnerabilities

This CVE is medium severity; 8 of 8 other CVEs affecting bolt/bolt are rated as high or higher (top: high).

CVE-2025-34086CVE-2024-7300CVE-2019-15484CVE-2019-15483CVE-2017-11128CVE-2017-11127CVE-2018-19933CVE-2019-10874

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 24, 2026