Red Hat Enterprise Linux DLX ELF backend bfd/elf32-dlx.c dlx_rtype_to_howto out-of-bounds write

Summaryinfo

A vulnerability, which was classified as very critical, has been found in Red Hat Enterprise Linux. This affects the function dlx_rtype_to_howto of the file bfd/elf32-dlx.c of the component DLX ELF backend. This manipulation causes out-of-bounds write. This vulnerability appears as CVE-2026-18220. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability has been found in Red Hat Enterprise Linux (affected version unknown) and classified as very critical. Affected by this vulnerability is the function dlx_rtype_to_howto of the file bfd/elf32-dlx.c of the component DLX ELF backend. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. The CWE definition for the vulnerability is CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

An out-of-bounds write vulnerability was found in the BFD library's DLX ELF backend (bfd/elf32-dlx.c) in GNU binutils. The dlx_rtype_to_howto() function maps ELF relocation types to internal howto structures but fails to perform adequate bounds checking on attacker-controlled relocation type values (via ELF32_R_TYPE(r_info)) before indexing into the dlx_elf_howto_table[] array. The DLX relocation type number space is non-contiguous (basic types 0-6, extended types at 0x10000+), but the default case in the switch statement allows arbitrary index values to reach the array access. A specially crafted ELF/DLX object file can trigger this out-of-bounds write when processed by any BFD-consuming tool (objdump, readelf, strip, ld, nm, objcopy). The vulnerability has been demonstrated to achieve arbitrary code execution via a File Stream Oriented Programming (FSOP) attack against glibc FILE structures (stderr), redirecting control flow to system(). Attack scenarios include CI/CD pipelines performing automated binary analysis, developer workstations running objdump/readelf on untrusted binaries, automated security scanning or malware analysis tools invoking binutils, and package build systems processing third-party code. Note: This vulnerability is only exploitable when binutils is built with the DLX backend enabled (typically via --enable-targets=all).

The advisory is shared at access.redhat.com. This vulnerability is known as CVE-2026-18220 since 07/29/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 07/29/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-50279). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• Operating System

Vendor

• Red Hat

Name

• Enterprise Linux

License

• commercial

Website

• Vendor: https://www.redhat.com/

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If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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