Three technical stories from today’s recap:

Ubuntu container escape: DepthFirst released an exploit for CVE-2026-80521 that reaches host root from a container on Ubuntu 26.04. The AF\UNIX flaw was fixed upstream, but affected distribution kernels still need the patch.

F5 BIG-IP APM RCE: CVE-2026-94127 is being exploited against vulnerable OAuth authorization-server configurations. Management-interface access is not required. Hotfixes are available.

Process Parameter Poisoning: Flashpoint tested Windows code injection through process initialization structures, avoiding common memory-writing APIs. The technique produced no alerts from the EDR controls tested in its lab.

More technical details and source links in today’s recap on CyberRecaps, and have an amazing day :)

F5 BIG-IP APM contains a heap-based buffer overflow vulnerability when access policy and an OAuth profile are configured on a virtual server. This vulnerability could allow an unauthenticated attacker to perform remote code execution.

Last updated 18 September 2024

The Diffie-Hellman Key Agreement Protocol allows remote attackers (from the client side) to send arbitrary numbers that are actually not public keys, and trigger expensive server-side DHE modular-exponentiation calculations, aka a D(HE)at or D(HE)ater attack. The client needs very little CPU resources and network bandwidth. The attack may be more disruptive in cases where a client can require a server to select its largest supported key size. The basic attack scenario is that the client must claim that it can only communicate with DHE, and the server must be configured to allow DHE.

Last updated 31 October 2024

Last updated 24 February 2025

In netstat in BusyBox through 1.37.0, local users can launch of network application with an argv[0] containing an ANSI terminal escape sequence, leading to a denial of service (terminal locked up) when netstat is used by a victim.

A flaw was found in rsync which could be triggered when rsync compares file checksums. This flaw allows an attacker to manipulate the checksum length (s2length) to cause a comparison between a checksum and uninitialized memory and leak one byte of uninitialized stack data at a time.

A stack overflow vulnerability exists in the libexpat library due to the way it handles recursive entity expansion in XML documents. When parsing an XML document with deeply nested entity references, libexpat can be forced to recurse indefinitely, exhausting the stack space and causing a crash. This issue could lead to denial of service (DoS) or, in some cases, exploitable memory corruption, depending on the environment and library usage.

A Heap Use After Free (UAF) vulnerability was discovered in the Schematron in the libxml2. The issue arises in the xmlSchematronGetNode function when processing XPath expressions in Schematron schema elements <sch:name path="..."/>, where a pointer to freed memory is returned and then accessed, leading to undefined behavior and potential crashes.

A null pointer dereference vulnerability was discovered in the libxml2. The issue occurs in the xmlSchematronFormatReport function when processing incorrect XPath expressions in Schematron schema reports, leading to undefined behavior and potential crashes.

A vulnerability was found in libxml2. Processing certain sch:name elements from the input XML file can trigger a memory corruption issue. This flaw allows an attacker to craft a malicious XML input file that can lead libxml to crash, resulting in a denial of service or other possible undefined behavior due to sensitive data being corrupted in memory.

In the Linux kernel, the following vulnerability has been resolved:

tls: separate no-async decryption request handling from async

If we're not doing async, the handling is much simpler. There's no reference counting, we just need to wait for the completion to wake us up and return its result.

We should preferably also use a separate cryptowait. I'm not seeing a UAF as I did in the past, I think aec7961916f3 ("tls: fix race between async notify and socket close") took care of it.

This will make the next fix easier.

Quadratic complexity when parsing some invalid inputs in encoding/pem

Panic when validating certificates with DSA public keys in crypto/x509

Excessive CPU consumption in ParseAddress in net/mail

Due to the design of the name constraint checking algorithm, the processing time of some inputs scale non-linearly with respect to the size of the certificate. This affects programs which validate arbitrary certificate chains.

A vulnerability exists in an undisclosed BIG-IP Configuration utility page that may allow an attacker to spoof error messages

Impact:

An attacker may trick authenticated BIG-IP users into accessing malicious links and reflect a spoofed error message in the victim's BIG-IP Configuration utility web browser session. This is a control plane issue; there is no data plane exposure.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

NGINX ngxhttpproxyv2module and ngxhttpgrpcmodule vulnerability

A use-after-free vulnerability was found in libxslt while parsing xsl nodes that may lead to the dereference of expired pointers and application crash.

Accessibility. A privacy issue was addressed by removing sensitive data.

Last updated 6 June 2026

A certificate with a URI which has a IPv6 address with a zone ID may incorrectly satisfy a URI name constraint that applies to the certificate chain.

Certificates containing URIs are not permitted in the web PKI, so this only affects users of private PKIs which make use of URIs.

Arbitrary code execution during build via line directives in cmd/go

In tar in BusyBox through 1.37.0, a TAR archive can have filenames hidden from a listing through the use of terminal escape sequences.

A vulnerability has been found in GNU Binutils 2.45. The affected element is the function elfswapshdr in the library bfd/elfcode.h of the component Linker. The manipulation leads to heap-based buffer overflow. The attack must be carried out locally. The exploit has been disclosed to the public and may be used. The identifier of the patch is 9ca499644a21ceb3f946d1c179c38a83be084490. To fix this issue, it is recommended to deploy a patch. The code maintainer replied with "[f]ixed for 2.46".

BIG-IP has a vulnerability where an authenticated user of any role may be able to create administrative user accounts through an undisclosed request to Traffic Management User Interface (TMUI).

Impact:

This vulnerability may allow an authenticated attacker with network access to the BIG-IP management interface to escalate privileges by creating administrative accounts on the BIG-IP system. There is no data plane exposure; this is a control plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

CVE-2024-42516 - this is the "complete" fix for the CVE-2023-38709 response splitting issue. The patch issued upstream for CVE-2023-38709 did not fix the vulnerability.