CVE-2025-69647: 
NixOS vulnerability analysis and mitigation

CVE-2025-69647 is a denial-of-service vulnerability in GNU Binutils readelf affecting versions through 2.45.1. A logic flaw in the DWARF loclists parsing code causes readelf to enter an infinite loop when processing a crafted binary with malformed DWARF loclists data, repeatedly printing the same table output without making forward progress. The vulnerability was published on March 9, 2026, with a patch available via sourceware.org and Microsoft. It carries a CVSS v3.1 base score of 6.2 (Medium) (Feedly, Microsoft MSRC).

The root cause is classified as CWE-835 (Loop with Unreachable Exit Condition / 'Infinite Loop'). The flaw resides in the DWARF loclists parsing logic within readelf: when encountering malformed loclists data in a crafted ELF binary, the parser fails to advance its internal position, causing it to repeatedly emit the same table output indefinitely. Exploitation requires only local access — no privileges are needed — and is triggered simply by passing a malicious binary file as input to readelf. A fix was committed to the binutils-gdb repository (sourceware.org patch, Bugzilla report).

Successful exploitation causes readelf to consume excessive CPU and I/O resources indefinitely, preventing the tool from completing its analysis and potentially degrading system performance. The impact is limited to availability — there is no confidentiality or integrity impact. Because readelf is a developer/analysis tool rather than a network-facing service, the blast radius is generally confined to the local system or build/CI environment where the malicious binary is processed (Feedly).

No confirmed in-the-wild exploitation has been observed, and no functional proof-of-concept exploit code is publicly available. The EPSS score is approximately 0.021%, indicating a very low probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. The attack requires local access and only involves supplying a crafted binary file to readelf (Feedly).

1. Craft a malicious ELF binary: Create or modify an ELF binary to include malformed DWARF loclists data — specifically, data that causes the loclists parser to fail to advance its read position (e.g., a loclists entry with an invalid or zero-length offset that causes the loop counter to stall).
2. Deliver the file to the target system: Place the crafted binary on a system where a vulnerable version of GNU Binutils (≤ 2.45.1) is installed, using any available local access method (e.g., shared filesystem, build pipeline injection, social engineering a developer).
3. Trigger the vulnerability: Execute readelf against the malicious binary, for example: readelf -a malicious.elf or readelf --debug-dump=loc malicious.elf.
4. Observe denial of service: readelf enters an infinite loop, printing the same DWARF loclists table output repeatedly, consuming CPU and I/O resources until the process is externally killed or the system becomes unresponsive (Feedly, Bugzilla report).

• Process: A readelf process running for an abnormally long time (minutes to hours) with consistently high CPU utilization and no sign of completion.
• Logs: Build system or CI/CD logs showing a readelf invocation that never exits or produces unbounded output before being killed by a timeout.
• File System: Presence of unexpected or externally supplied ELF binaries in build directories, temporary folders, or developer workstations that were not produced by the local build process.
• I/O: Unusually high disk write activity associated with a readelf process, consistent with unbounded output being redirected to a file or log (Feedly).

Update GNU Binutils to a version after 2.45.1 by applying the upstream patch committed to the binutils-gdb repository. Microsoft has also released updated packages for Azure Linux 3 (azl3_binutils). As a workaround, restrict execution of readelf on untrusted or externally sourced binary files, and consider sandboxing or time-limiting readelf invocations in automated build and CI/CD pipelines. Fedora users can apply the available mingw-binutils update (sourceware.org patch, Microsoft MSRC).

The Yocto Project security mailing list has tracked this CVE across multiple messages, indicating awareness in the embedded Linux build community. Fedora has issued a security update for mingw-binutils addressing this and related issues. No notable researcher commentary or significant social media discussion has been identified beyond routine vulnerability tracking (Yocto Security List, Fedora Advisory).