VulnerabilityPublished 25 Sep 2026Updated 28 Sep 2026

CVE-2026-92842: PHP · Heap-based Buffer Overflow

Affects PHPSource CVE Database V5

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Not known to be exploited · CVSS 5.9 Medium · fixed in 8.5.11 : update PHP when convenient.

Data as of 9 Nov 2026, 23:24 UTC

CVSS 3.1 base score

5.9Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 20% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 8.5.11, 8.4.26, 8.3.35 +1

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector: Network
Attack Complexity: High
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 9 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade PHP to 8.5.11, 8.4.26, 8.3.35 or 8.2.34.

Affected software

Product	Affected	Fixed in
PHP GroupPHP	Affected ≥ 8.5.*, < 8.5.11	Fixed in 8.5.11
PHP GroupPHP	Affected ≥ 8.4.*, < 8.4.26	Fixed in 8.4.26
PHP GroupPHP	Affected ≥ 8.3.*, < 8.3.35	Fixed in 8.3.35
PHP GroupPHP	Affected ≥ 8.2.*, < 8.2.34	Fixed in 8.2.34

AI-suggested

If you cannot patch yet, avoid using the affected stream filters with untrusted input or the line-break-chars option.

Description

CVE-2026-92842 is a medium severity heap-based buffer overflow vulnerability in PHP related to the convert.base64-encode, convert.quoted-printable-encode, and convert.quoted-printable-decode stream filters. The issue arises because the filters accept a line-break-chars option whose length is tracked separately from the string itself. The filter constructors duplicate the value using pestrdup(), which stops at the first NUL byte but retains the original length. This discrepancy allows the filter to read past the allocated buffer when emitting a line break, potentially leaking adjacent heap memory into the output.

Impact

The vulnerability allows reading of adjacent heap memory beyond the intended buffer, potentially leaking sensitive information. The CVSS score of 5.9 indicates a medium severity impact with high confidentiality impact but no integrity or availability impact. There is no indication of remote code execution or denial of service from the provided data.

Summary

This vulnerability in PHP's stream filters for base64 and quoted-printable encoding/decoding involves improper handling of the line-break-chars option. The duplication function pestrdup() truncates at the first NUL byte but the length used later remains the original, causing a heap-based buffer overflow when the filter emits a line break. This results in reading beyond the allocated buffer and including adjacent heap bytes in the output, which can lead to information disclosure.

CWE-122Heap-based Buffer Overflow (opens in a new tab)
Variant weaknessLikelihood of exploit: HighCWE Top 25 (2025): #16
The product writes past the end of a buffer that was allocated on the heap.
Pre-design: Use a language or compiler that performs automatic bounds checking.
Architecture and Design
Use an abstraction library to abstract away risky APIs. Not a complete solution.
Operation · Build and Compilation · Environment Hardening
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index…
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Forced Integer Overflow (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-125Out-of-bounds Read (opens in a new tab)
Base weaknessCWE Top 25 (2025): #8
The product reads data past the end, or before the beginning, of the intended buffer.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Architecture and Design · Language Selection
Use a language that provides appropriate memory abstractions.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Overread Buffers (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/php/php-src/security/advisories/GHSA-88hq-2827-7pg6 (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 17 Oct 2026, 23:10 UTC

WeaknessesCWE-122, CWE-125

Technical details

References

Community reviews

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