high CVSS 7.5 EPSS <0.1%

CVE-2026-7258·PHP vulnerability

In PHP versions 8.2.* before 8.2.31, 8.3.* before 8.3.31, 8.4.* before 8.4.21, and 8.5.* before 8.5.6, some functions, including urldecode(), pass signed char to ctype functions (like isxdigit()). On the systems with default signed char and optimized table-lookup ctype functions - such as NetBSD - this can lead to accessing array with negative offset, which can trigger a denial of service.

Severity
high
Software
PHP
Fixed in
8.5.6
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at <0.1% — higher than 7% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Read the two together. CVE-2026-7258 scores 7.5 on CVSS, so a successful attack would be serious — but at <0.1%, almost nobody is currently attempting it. That is a different situation from a flaw under mass exploitation, and it is usually the difference between patching on your next maintenance window and patching tonight.

Affected versions

From: 8.5.0

Until: 8.5.6

Fixed in: 8.5.6

How to fix this CVE

Update PHP immediately to version 8.5.6 or later to resolve a denial-of-service vulnerability affecting the urldecode() function and related ctype operations. This flaw can cause array access violations on systems with signed char defaults, resulting in application crashes. Verify your current PHP version and apply the security patch without delay.

sudo dnf update php-8.5.6 || sudo dnf upgrade php

Defensia detects this vulnerability

How to check if you are affected

  1. Run 'php -v' to check the currently installed PHP version and confirm it is below 8.5.6.
  2. Verify which PHP modules are loaded by running 'php -m' to assess if URL-related functions are actively used.
  3. Check application error logs in /var/log/php-fpm.log or /var/log/apache2/error.log for segmentation faults or array access warnings.
  4. After patching, re-run 'php -v' and confirm the version is 8.5.6 or higher, then restart PHP with 'sudo systemctl restart php-fpm' or equivalent.

FAQ

What is CVE-2026-7258?

CVE-2026-7258 is a denial-of-service vulnerability in PHP where the urldecode() function and related ctype operations pass signed characters to system functions that expect unsigned values. On systems with signed char defaults, this triggers negative array offsets, causing crashes and service unavailability.

Is CVE-2026-7258 being actively exploited?

No, this vulnerability is not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog and no public exploits are available. However, the DoS impact warrants immediate patching to prevent potential future exploitation.

What versions of PHP are affected by CVE-2026-7258?

PHP versions 8.5.0 through 8.5.5 are vulnerable. The vulnerability is fixed in PHP 8.5.6 and later. Earlier branch versions (8.2, 8.3, 8.4) have separate fixed versions in their respective patch releases.

How do I check if my server is vulnerable to CVE-2026-7258?

Run 'php -v' and check if your version falls between 8.5.0 and 8.5.5. If yes, your server is vulnerable and requires immediate upgrade to 8.5.6 or later.

Does Defensia detect CVE-2026-7258?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If PHP is installed on a monitored server, CVE-2026-7258 will appear in your dashboard with remediation steps.

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References

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