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CVE-2009-3555 is a TLS/SSL renegotiation vulnerability that lets a man-in-the-middle attacker prepend unauthenticated, chosen plaintext to a connection before renegotiation. Because vulnerable TLS and SSL implementations do not cryptographically bind the renegotiation handshake to the original session, the injected data can be processed in the authenticated post-renegotiation context. The flaw affects HTTPS and other TLS-protected protocols, but does not allow an attacker to decrypt or modify traffic after a session has been negotiated.
Affected software included older versions of Microsoft IIS, Apache mod_ssl, OpenSSL, GnuTLS, Mozilla NSS, Cisco products, and Java's SunJSSE. Java mitigated the issue first by disabling renegotiation by default and later by implementing RFC 5746 secure renegotiation; its interoperable mode permits legacy initial connections while blocking unsafe legacy renegotiation. Organizations should ensure TLS stacks support RFC 5746 and disable or restrict insecure renegotiation where legacy compatibility is not required.
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4 events from the most recent confirmed update back to the earliest known activity.
The Java SE and Java for Business Critical Patch Update included SunJSSE Phase 1 mitigation, which disabled SSL/TLS renegotiation by default.
CVE-2009-3555 was published for the TLS/SSL renegotiation vulnerability, also known as the Project Mogul plaintext-injection issue. Vulnerable implementations fail to cryptographically bind renegotiation handshakes to the existing connection.
Marsh Ray disclosed the TLS/SSL renegotiation design issue, which permits a man-in-the-middle attacker to inject chosen plaintext as a prefix of a TLS connection.
SunJSSE Phase 2 added RFC 5746 secure-renegotiation support in JDK/JRE 6 Update 22, 5.0 Update 26, and 1.4.2 Update 28. The default interoperable mode permits legacy initial connections but prevents unsafe legacy renegotiation.
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A critical vulnerability tracked as **`CVE-2026-55953`** affects Erlang/OTP SSL clients using **TLS 1.2 and earlier** as well as **DTLS**, allowing an on-path attacker to bypass server authentication and intercept supposedly secure sessions. The flaw occurs because the client does not verify that the cipher suite selected by the server was actually offered in the `ClientHello`, enabling an attacker to force an anonymous cipher suite and complete the handshake without certificate validation or hostname checking. Once the connection is established, the attacker can read and modify traffic; **TLS 1.3 is not affected** because it already performs the required cipher-suite membership check. The issue affects Erlang/OTP from **`OTP 17.0`** up to the patched releases **`27.3.4.15`**, **`28.5.0.4`**, and **`29.0.4`**, with corresponding SSL fixes in **`11.2.12.11`**, **`11.6.0.4`**, and **`11.7.4`**. Erlang/OTP maintainers addressed the bug in July with code changes to `ssl_handshake.erl` that add a pre-TLS 1.3 client cipher-suite validation check and trigger a fatal `illegal_parameter` alert if the negotiated suite was not advertised by the client. The vulnerability carries a **CVSS 4.0 score of 9.1** and is classified under **`CWE-757`**.
Jul 28, 2026
Microsoft patched **`CVE-2026-47291`**, a remotely exploitable flaw in **Windows `HTTP.sys`** that can cause denial of service or potentially **kernel-level remote code execution** on systems using the HTTP protocol stack behind IIS and other applications. The bug stems from an **integer overflow** while `HTTP.sys` expands a per-request buffer reference array during **HTTP/1.x header parsing over TLS**; the array's 16-bit capacity can wrap to zero, leading to a large **kernel pool heap buffer overflow** during memory movement operations. Exploitation requires a remote, unauthenticated attacker to send a specially crafted **HTTPS** request with many header lines, placing each header in a separate **TLS application data record** so each becomes a distinct buffer reference. The issue is described as reachable only on the **HTTP/1.x over TLS** path, not the HTTP/2 or HTTP/3 parser paths, and it depends on the target accepting an unusually large request; keeping the **`MaxRequestBytes`** registry setting at or below **65,535 bytes** is cited as a practical mitigation, while applying Microsoft's June 2026 patch is the recommended fix. Detection guidance includes inspecting decrypted HTTPS traffic for excessive HTTP/1.x header lines or, without decryption, looking for sustained connections carrying many small TLS application data records.
Jul 11, 2026
Researchers disclosed the **Terrapin** attack, a man-in-the-middle flaw in the SSH transport protocol tracked as **`CVE-2023-48795`**, that can corrupt the handshake and strip or disable negotiated security features. The attack exploits sequence number manipulation and prefix truncation in the SSH Binary Packet Protocol, affecting connections that use **ChaCha20-Poly1305** and certain **CBC with Encrypt-then-MAC** configurations. The issue impacts OpenSSH before **9.6** and a broad set of SSH clients, servers, libraries, and products; researchers reported that **77%** of Internet-exposed SSH servers supported at least one vulnerable mode and **57%** preferred one. The disclosure also highlighted implementation-specific flaws in **AsyncSSH**—**`CVE-2023-46445`** and **`CVE-2023-46446`**—that could enable more severe outcomes, including redirecting a victim into an attacker-controlled shell account under the right conditions. Ruhr University Bochum researchers released technical details, proof-of-concept code, and a scanner after coordinated vendor fixes, while maintainers shipped updates including **OpenSSH 9.6**, **PuTTY 0.8**, **libssh 0.10.6/0.9.8**, and **AsyncSSH 2.14.1/2.14.2**. Defenders were urged to patch affected software and, where possible, disable vulnerable cipher modes in favor of safer options such as **AES-GCM**.
Jun 29, 2026