CVE-2026-5090

Description

Template::Plugin::HTML versions through 3.102 for Perl allows HTML and JavaScript to be injected. The html_filter function did not escape single quotes. HTML attributes inside of single quotes could be have code injected. For example, the variable "var" in <a id='ref' title='[% var | html %]'> would not be properly escaped. An attacker could insert some limited HTML and JavaScript, for example, var = " ' onclick='while (true) { alert(1) }'" Note that arbitrary HTML and JavaScript would be difficult to inject, because angle brackets, ampersands and double-quotes would still be escaped.

CVSS Details

CVSS Score

6.1

Severity

MEDIUM

CVSS Vector

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

Configurations (Affected Products)

No configuration data available.

Template::Plugin::HTML <= 3.102

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

# Vulnerable template snippet
# <a id='ref' title='[% var | html %]'>

# PoC Input value for 'var'
# This payload breaks out of the single quote attribute and injects an onclick event
my $var = "' onclick='while (true) { alert(1) }'";

# Expected Rendered HTML:
# <a id='ref' title='' onclick='while (true) { alert(1) }''>

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-5090
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-5090
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-5090/
[4] VulDB https://vuldb.com/cve/CVE-2026-5090
[5] https://github.com/abw/Template2/issues/327
[6] https://github.com/abw/Template2/pull/337/changes/11c78a7a771d4af505efeb754a0b8775689c2eae
[7] http://www.openwall.com/lists/oss-security/2026/05/19/40

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-5090", "sourceIdentifier": "9b29abf9-4ab0-4765-b253-1875cd9b441e", "published": "2026-05-19T22:16:39.003", "lastModified": "2026-05-20T14:17:02.610", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "Template::Plugin::HTML versions through 3.102 for Perl allows HTML and JavaScript to be injected.\n\nThe html_filter function did not escape single quotes. HTML attributes inside of single quotes could be have code injected.  For example, the variable \"var\" in\n\n    <a id='ref' title='[% var | html %]'>\n\nwould not be properly escaped. An attacker could insert some limited HTML and JavaScript, for example,\n\n    var = \" ' onclick='while (true) { alert(1) }'\"\n\nNote that arbitrary HTML and JavaScript would be difficult to inject, because angle brackets, ampersands and double-quotes would still be escaped."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N", "baseScore": 6.1, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "CHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 2.7}]}, "weaknesses": [{"source": "9b29abf9-4ab0-4765-b253-1875cd9b441e", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-79"}]}], "references": [{"url": "https://github.com/abw/Template2/issues/327", "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"}, {"url": "https://github.com/abw/Template2/pull/337/changes/11c78a7a771d4af505efeb754a0b8775689c2eae", "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"}, {"url": "http://www.openwall.com/lists/oss-security/2026/05/19/40", "source": "af854a3a-2127-422b-91ae-364da2661108"}]}}