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Mallory
Medium

OpenSSL HTTP client no_proxy IPv6 out-of-bounds read

IdentifiersCVE-2025-9232CWE-125· Out-of-bounds Read

CVE-2025-9232 is an out-of-bounds read in OpenSSL's HTTP client API no_proxy handling. An application using the OpenSSL HTTP client API functions may trigger the flaw when the no_proxy environment variable is set and the host portion of the authority component of an HTTP URL is an IPv6 address. The vulnerable code is also reachable indirectly via OpenSSL's OCSP client functions and CMP client implementation, although the associated URLs in those paths are considered unlikely to be attacker-controlled. OpenSSL states the vulnerable code was introduced in patch releases 3.0.16, 3.1.8, 3.2.4, 3.3.3, 3.4.0, and 3.5.0. The issue is assessed as low severity because exploitation requires attacker influence over the URL input and, in the vulnerable code path, the out-of-bounds read can only trigger a crash.

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ANALYST BRIEF

Impact, mitigation & remediation

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Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation causes an application crash, resulting in denial of service. Based on the provided vendor description, the out-of-bounds read does not provide code execution or data disclosure and is limited to crash/DoS impact in the vulnerable path.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, reduce exposure by preventing attacker-controlled URLs from reaching OpenSSL HTTP client API consumers, including any application logic that passes externally supplied HTTP URLs into OpenSSL HTTP, OCSP, or CMP client functionality. Where operationally feasible, unset or tightly control the no_proxy environment variable on affected processes. There is no general vendor workaround in the provided content.

Remediation

Patch, then assume compromise.

Upgrade OpenSSL to a fixed release. The provided content identifies patched versions as 3.5.4, 3.4.3, 3.3.5, 3.2.6, and 3.0.18 for the supported 3.x branches. Downstream vendors should also consume package updates that incorporate these fixes. Restart affected applications or services after updating so they load the corrected OpenSSL library.
PUBLIC EXPLOITS

Exploits

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VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

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VendorProductType
FreebsdFreebsdapplication
OpenSSL Software FoundationOpensslapplication

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Social activity21

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