PatchTheCVECVE-2019-19246: Oniguruma through 6.9.3, as used in PHP 7.3.x and other products, has a heap-based buffer over-read in str_low
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HIGH 7.5REMOTEWATCHLISTUPGRADEUPGRADEMITIGATE
CVE-2019-19246 is a high-severity flaw (CVSS 7.5) affecting oniguruma, php, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Oniguruma through 6.9.3, as used in PHP 7.3.x and other products, has a heap-based buffer over-read in str_lower_case_match in regexec.c.
Why this priority
- High severity
- Remotely exploitable, no login, no user action
- On your watchlist
A fixed release or distro patch exists.
Risk facts
| CVSS score | 7.5 (High) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 3.0% (top 13%) |
| CISA exploited list | No |
| Weakness | CWE-125 |
| Published | 2019-11-25 |
| Last modified | 2026-06-17 |
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
oniguruma project oniguruma UPGRADE
Affected: <= 6.9.3
Fixed in: newer than 6.9.3
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy oniguruma || rpm -q oniguruma || oniguruma --version
2. UPGRADE to newer than 6.9.3 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade oniguruma
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade oniguruma
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
php php UPGRADE
Affected: >= 7.3.0 and < 7.3.10
Fixed in: 7.3.10
Safe to downgrade to: a release before 7.3.0
1. Check installed version
apt-cache policy php || rpm -q php || php --version
2. UPGRADE to 7.3.10 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade php
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade php
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
3. If no update is available yet, DOWNGRADE to a release before 7.3.0 (Debian / Ubuntu)
apt-cache madison php
sudo apt install php=<VERSION_BEFORE_7.3.0>
sudo apt-mark hold php
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list php
sudo dnf downgrade php-<VERSION_BEFORE_7.3.0>
sudo dnf versionlock add php
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: 31
Fixed in: no fixed release known
Safe to downgrade to: a release before 31
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.
canonical ubuntu linux MITIGATE
Affected: 14.04
Fixed in: no fixed release known
Safe to downgrade to: a release before 14.04
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.
debian debian linux MITIGATE
Affected: 8.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 8.0
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.
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-2019-19246?
oniguruma: upgrade to newer than 6.9.3; php: upgrade to 7.3.10; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2019-19246 being exploited?
CVE-2019-19246 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-2019-19246 affect?
CVE-2019-19246 affects oniguruma, php, fedora. Severity is high (CVSS 7.5). Oniguruma through 6.9.3, as used in PHP 7.3.x and other products, has a heap-based buffer over-read in str_lower_case_match in regexec.c.
How urgent is CVE-2019-19246?
Priority 58/100. High severity; Remotely exploitable, no login, no user action; On your watchlist
Software pages
PHP vulnerabilities · Ubuntu vulnerabilities · Debian vulnerabilities
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