CVE-2019-13225: A NULL Pointer Dereference in match_at() in regexec.c in Oniguruma 6.9.2 allows attackers to potentially cause

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MEDIUM 6.5DOWNGRADEMITIGATE

CVE-2019-13225 is a medium-severity flaw (CVSS 6.5) affecting oniguruma, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A NULL Pointer Dereference in match_at() in regexec.c in Oniguruma 6.9.2 allows attackers to potentially cause denial of service by providing a crafted regular expression. Oniguruma issues often affect Ruby, as well as common optional libraries for PHP and Rust.

Why this priority

No elevated risk signals yet

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

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	2.1% (top 18%)
CISA exploited list	No
Weakness	CWE-476
Published	2019-07-10
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: fedoraproject · oniguruma project

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

Am I affected?

Timeline

2019-07-10 14:15 UTCPublished CVE record published
2026-06-17 02:16 UTCUpdated Record last modified

oniguruma project oniguruma DOWNGRADE

Affected: 6.9.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 6.9.2

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 6.9.2 (Debian / Ubuntu)

apt-cache madison oniguruma sudo apt install oniguruma=<VERSION_BEFORE_6.9.2> sudo apt-mark hold oniguruma

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

dnf --showduplicates list oniguruma sudo dnf downgrade oniguruma-<VERSION_BEFORE_6.9.2> sudo dnf versionlock add oniguruma

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.

fedoraproject fedora MITIGATE

Affected: 29 · 30

Fixed in: no fixed release known

Safe to downgrade to: a release before 29

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2019-13225?

oniguruma: downgrade or apply the listed mitigation; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2019-13225 being exploited?

CVE-2019-13225 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-2019-13225 affect?

CVE-2019-13225 affects oniguruma, fedora. Severity is medium (CVSS 6.5). A NULL Pointer Dereference in match_at() in regexec.c in Oniguruma 6.9.2 allows attackers to potentially cause denial of service by providing a crafted regular expression. Oniguruma issues often affect Ruby, as well as common optional libra

How urgent is CVE-2019-13225?

Priority 43/100. No elevated risk signals yet.

Software pages

PHP vulnerabilities · Ruby vulnerabilities

Related CVEs

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CVE-2019-19204 HIGH 7.5 UPGRADE MITIGATE An issue was discovered in Oniguruma 6.x before 6.9.4_rc2
CVE-2019-19203 HIGH 7.5 UPGRADE MITIGATE An issue was discovered in Oniguruma 6.x before 6.9.4_rc2
CVE-2019-19012 CRITICAL 9.8 UPGRADE MITIGATE An integer overflow in the search_in_range function in regexec.c in Oniguruma 6.x before 6.9.4_rc2 leads to an
CVE-2019-13224 CRITICAL 9.8 DOWNGRADE UPGRADE A use-after-free in onig_new_deluxe() in regext.c in Oniguruma 6.9.2 allows attackers to potentially cause inf

References

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