How severe is CVE-2010-1866?

CVE-2010-1866 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2010-1866 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2010-1866?

CVE-2010-1866 primarily affects Php. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2010-1866?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2010-1866 published?

CVE-2010-1866 was published on 2010-05-07 and last updated on 2026-06-16.

CVE-2010-1866

CVE-2010-1866 is a critical-severity vulnerability in Php with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-190.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 7% (93rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-190
Affected product: Php
Published: 2010-05-07
Last modified: 2026-06-16

Description

The dechunk filter in PHP 5.3 through 5.3.2, when decoding an HTTP chunked encoding stream, allows context-dependent attackers to cause a denial of service (crash) and possibly trigger memory corruption via a negative chunk size, which bypasses a signed comparison, related to an integer overflow in the chunk size decoder.

Frequently asked questions

What is CVE-2010-1866?: The dechunk filter in PHP 5.3 through 5.3.2, when decoding an HTTP chunked encoding stream, allows context-dependent attackers to cause a denial of service (crash) and possibly trigger memory corruption via a negative chunk size, which bypasses a signed comparison, related to an integer overflow in the chunk size decoder.
How severe is CVE-2010-1866?: CVE-2010-1866 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2010-1866 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2010-1866?: CVE-2010-1866 primarily affects Php. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2010-1866?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2010-1866 published?: CVE-2010-1866 was published on 2010-05-07 and last updated on 2026-06-16.

References

Affected products (7)

cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
cpe:2.3:o:opensuse:opensuse:11.1:*:*:*:*:*:*:*
cpe:2.3:o:opensuse:opensuse:11.2:*:*:*:*:*:*:*
cpe:2.3:o:opensuse:opensuse:11.3:*:*:*:*:*:*:*
cpe:2.3:o:suse:linux_enterprise:10.0:sp3:*:*:*:*:*:*
cpe:2.3:o:suse:linux_enterprise:11.0:-:*:*:*:*:*:*
cpe:2.3:o:suse:linux_enterprise:11.0:sp1:*:*:*:*:*:*

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