CVE-2025-11083: 
NixOS vulnerability analysis and mitigation

CVE-2025-11083 is a heap-based buffer overflow vulnerability in GNU Binutils 2.45, specifically in the elf_swap_shdr function within the bfd/elfcode.h library of the Linker component. The vulnerability was published on September 27, 2025, and a proof-of-concept exploit has been publicly disclosed. It affects GNU Binutils version 2.45, with downstream impact on distributions and products that bundle this version, including IBM CICS TX Standard and Microsoft Azure Linux packages. The CVSS v3.1 base score is 7.8 (High), reflecting a local attack vector with low privileges required and high impacts on confidentiality, integrity, and availability (Feedly, MSRC).

The root cause is improper restriction of operations within the bounds of a memory buffer (CWE-119 / CWE-122 — Heap-based Buffer Overflow) in the elf_swap_shdr function of bfd/elfcode.h. An attacker with local access can manipulate input to this function — likely by supplying a crafted ELF binary to a Binutils tool such as ld or objcopy — causing a heap buffer overflow. No user interaction is required beyond the attacker having low-privileged local access. A proof-of-concept exploit has been publicly disclosed via the GNU Binutils bug tracker, and the upstream patch is identified by commit 9ca499644a21ceb3f946d1c179c38a83be084490 (Sourceware Bugzilla, Sourceware Git).

Successful exploitation could allow a local attacker to achieve arbitrary code execution, potentially gaining elevated privileges on the affected system. The vulnerability carries high impacts on confidentiality, integrity, and availability, meaning an attacker could read sensitive memory, corrupt data, or crash Binutils-based toolchain processes. In build environments or CI/CD pipelines where Binutils processes untrusted binary inputs, exploitation could lead to supply chain compromise or lateral movement within development infrastructure (Feedly, MSRC).

A proof-of-concept exploit has been publicly disclosed on the Sourceware Bugzilla tracker since the time of initial disclosure in late September 2025. The EPSS score is approximately 0.013% (0.000130), indicating a currently low probability of widespread exploitation. There is no evidence of active in-the-wild exploitation or threat actor attribution at this time, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. The CVSSv4 exploit maturity is rated as PROOF_OF_CONCEPT (Feedly).

1. Reconnaissance: Identify systems running GNU Binutils 2.45 or downstream distributions that have not yet applied the patch (e.g., unpatched Ubuntu, RHEL, SUSE, or Fedora systems with binutils packages).
2. Craft malicious ELF binary: Create a specially crafted ELF binary with malformed section header data designed to trigger an out-of-bounds write in the elf_swap_shdr function when processed by Binutils tools.
3. Trigger vulnerable code path: Execute a Binutils tool (e.g., ld, objcopy, readelf) against the crafted ELF file as a low-privileged local user, causing the elf_swap_shdr function in bfd/elfcode.h to process the malformed section headers.
4. Heap overflow: The malformed input causes a heap-based buffer overflow, potentially overwriting adjacent heap metadata or function pointers.
5. Achieve code execution: Leverage the heap corruption to redirect execution flow, potentially executing arbitrary code in the context of the Binutils process (Sourceware Bugzilla).

• File System: Presence of unusual or malformed ELF binaries submitted to Binutils tools; unexpected output files or core dumps from ld, objcopy, or related tools.
• Logs: Crash logs or segmentation fault reports from Binutils processes (e.g., ld, objcopy) in system logs (/var/log/syslog, journalctl); application-level error messages referencing bfd/elfcode.h or elf_swap_shdr.
• Process: Unexpected child processes spawned from Binutils tools; Binutils processes consuming abnormal memory or crashing repeatedly when processing specific input files.
• Network: In build/CI environments, unexpected outbound connections from build servers following Binutils tool execution could indicate post-exploitation activity.

The upstream fix is targeted for GNU Binutils 2.46, identified by patch commit 9ca499644a21ceb3f946d1c179c38a83be084490. Multiple Linux distributions have released patched packages: Ubuntu (USN-7847-1, USN-7919-1), Red Hat/RHEL (RHSA-2025:23232, RHSA-2025:23233, RHSA-2026:0052, and others), SUSE (SUSE-2025-4096-1), AlmaLinux, Rocky Linux, and Oracle Linux. Users should upgrade their binutils packages to the patched versions provided by their distribution. As a workaround, restrict local user access to systems running vulnerable Binutils versions and avoid processing untrusted ELF binaries with affected tools until patched (Ubuntu Advisory, Red Hat Advisory, Sourceware Git).

The GNU Binutils maintainer confirmed the fix, stating it is "[f]ixed for 2.46". Multiple Linux distributions (Ubuntu, Red Hat, SUSE, AlmaLinux, Rocky Linux, Oracle Linux, Fedora) have issued security advisories and patched packages, indicating broad industry response. IBM also issued a security bulletin addressing the vulnerability in IBM CICS TX Standard. No significant social media discussion or notable independent researcher commentary has been identified beyond standard vulnerability tracking and distribution advisories (IBM Bulletin, Ubuntu Advisory).