CVE-2026-45753Network attack vector

Cross-site scripting via omitted URL attribute sanitization

Published Jul 14, 2026 · Updated Jul 14, 2026

Cross-site scripting in affected Symfony HTML Sanitizer releases allows attackers to execute script through sanitized untrusted HTML. UrlAttributeSanitizer::getSupportedAttributes() omits action, formaction, poster, and cite, so DomVisitor skips scheme validation and preserves javascript URIs. Exploitation requires a deliberately permissive attribute configuration; action and formaction payloads also require a victim to submit a form or click a button.

CVSS severity2.1
Low
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in affected Symfony HTML Sanitizer releases allows attackers to execute script through sanitized untrusted HTML. UrlAttributeSanitizer::getSupportedAttributes() omits action, formaction, poster, and cite, so DomVisitor skips scheme validation and preserves javascript URIs. Exploitation requires a deliberately permissive attribute configuration; action and formaction payloads also require a victim to submit a form or click a button.

The record

CVE
CVE-2026-45753
Published
Jul 14, 2026
Updated
Jul 14, 2026
Vendor
Symfony
Product
Symfony
Classifications
CWE-184, CWE-79, T1059.007
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=>= 6.1.0-BETA1, < 6.4.40
  2. Affected versionversion=>= 7.0.0-BETA1, < 7.4.12
  3. Affected versionversion=>= 8.0.0-BETA1, < 8.0.12

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Symfony · Symfonyversion=>= 6.1.0-BETA1, < 6.4.40; version=>= 7.0.0-BETA1, < 7.4.12; version=>= 8.0.0-BETA1, < 8.0.12
Symfony · Symfony HTML Sanitizerversion=>= 6.1.0-BETA1, < 6.4.40; version=>= 7.0.0-BETA1, < 7.4.12; version=>= 8.0.0-BETA1, < 8.0.12

Published CVSS scores

2.1GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A: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.

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-184Incomplete List of Disallowed Inputs
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007Command and Scripting Interpreter: JavaScript

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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