CVE-2026-13732
Description
A flaw was found in GDB's STABS debug format parser. The read_member_functions() function in gdb/stabsread.c contains a linked list removal bug in the code that separates destructor and non-destructor member functions of C++ classes. The bug causes the destructor entries to remain in the main function list while the list length counter is decremented, resulting in an out-of-bounds write when the function list is copied to its final allocated array. An attacker can craft an ELF binary with malicious .stab and .stabstr sections that triggers this out-of-bounds write when a user opens the file in GDB and performs any symbol-inspection operation such as setting a breakpoint. The inferior process does not need to be executed. Under controlled conditions, this was demonstrated to achieve execution of arbitrary commands within the GDB process.
Statement
This flaw affects the STABS debug format parser in GDB, which is present and active in all currently supported Red Hat product streams that ship GDB. The STABS format is a legacy debug information format predating DWARF that GDB parses automatically from .stab/.stabstr ELF sections. While GCC removed STABS emitting support in GCC 13 and GDB deprecated STABS parsing in GDB 17, all deployed GDB versions parse STABS data without user opt-in. An attacker can embed STABS sections in any ELF binary, including one compiled with DWARF debug information, and GDB will parse both. The vulnerability requires the user to open the crafted binary in GDB and issue a symbol-inspection command, which is normal GDB usage.
Mitigation
The following practices would help for avoiding exposure and mitigate this
flaw:
- Do not open untrusted or unknown ELF binaries in GDB without first
stripping debug sections. Use `objcopy --remove-section=.stab
--remove-section=.stabstr <binary>` before debugging.
- Use `readelf -S <binary> | grep stab` to check for the presence of
STABS sections before opening a binary in GDB. Legitimate modern
binaries use DWARF, not STABS.
- Consider using LLDB or other debuggers that do not support STABS for
analysis of untrusted binaries.
- For automated environments (CI, test farms) that invoke GDB on
potentially untrusted binaries, run GDB in a sandboxed or containerized
environment with restricted filesystem access.
- GDB 17+ deprecates STABS support but still parses it. GDB 18 (expected
late 2026/2027) will remove STABS support entirely.
- GCC removed STABS emitting in GCC 13 (2023), so legitimately compiled
binaries from recent GCC versions will not contain STABS data.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7 | N/A | 7.8 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | High | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | Required | N/A | Required |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
Write operations could cause memory corruption. In some cases, an adversary can modify control data such as return addresses in order to execute unexpected code.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
Attempting to access out-of-range, invalid, or unauthorized memory could cause the product to crash.
Other
Technical Impact: Unexpected State
Subsequent write operations can produce undefined or unexpected results.
Acknowledgements
Red Hat would like to thank JD Marsters (Bhut Red) for reporting this issue.
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