CVE-2019-13948: SyGuestBook A5 Version 1.2 allows stored XSS because the isValidData function in include/functions.php does no

Routine

MEDIUM 5.4DOWNGRADE

CVE-2019-13948 is a medium-severity flaw (CVSS 5.4) affecting syguestbook a5. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

SyGuestBook A5 Version 1.2 allows stored XSS because the isValidData function in include/functions.php does not properly block XSS payloads, as demonstrated by a crafted use of the onerror attribute of an IMG element.

Why this priority

Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.7% (top 47%)
CISA exploited list	No
Weakness	CWE-79
Published	2019-07-18
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: syguestbook a5 project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2019-07-18 16:15 UTCPublished CVE record published
2026-06-17 02:17 UTCUpdated Record last modified

syguestbook a5 project syguestbook a5 DOWNGRADE

Affected: 1.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.2

1. Check installed version

apt-cache policy syguestbook-a5 || rpm -q syguestbook-a5 || syguestbook-a5 --version

2. No fixed release: DOWNGRADE to a release before 1.2 (Debian / Ubuntu)

apt-cache madison syguestbook-a5 sudo apt install syguestbook-a5=<VERSION_BEFORE_1.2> sudo apt-mark hold syguestbook-a5

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list syguestbook-a5 sudo dnf downgrade syguestbook-a5-<VERSION_BEFORE_1.2> sudo dnf versionlock add syguestbook-a5

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

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-2019-13948?

syguestbook a5: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2019-13948 being exploited?

CVE-2019-13948 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-2019-13948 affect?

CVE-2019-13948 affects syguestbook a5. Severity is medium (CVSS 5.4). SyGuestBook A5 Version 1.2 allows stored XSS because the isValidData function in include/functions.php does not properly block XSS payloads, as demonstrated by a crafted use of the onerror attribute of an IMG element.

How urgent is CVE-2019-13948?

Priority 37/100. Public exploit reference

Software pages

PHP vulnerabilities

Related CVEs

CVE-2019-13950 MEDIUM 5.4 DOWNGRADE index.php?c=admin&a=index in SyGuestBook A5 Version 1.2 has stored XSS via a reply to a comment.
CVE-2019-13949 HIGH 8.8 DOWNGRADE SyGuestBook A5 Version 1.2 has no CSRF protection mechanism, as demonstrated by CSRF for an index.php?c=Admini

References

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