CVE-2026-77214
Description
A flaw was found in expat. A remote attacker can exploit this vulnerability through repeated parse buffer operations with unvalidated buffer lengths, causing a heap buffer over-read. This issue primarily leads to information disclosure by leaking adjacent heap memory contents, which could assist in bypassing security mitigations such as Address Space Layout Randomization (ASLR), or result in a Denial of Service (DoS) by crashing the application.
Statement
This vulnerability is rated as an Important severity because the Expat XML parser is ubiquitous across Red Hat Enterprise Linux environments, frequently handling untrusted inputs in network-facing services and runtime environments. When applications process incoming XML data through repeated chunked parsing calls, an unauthenticated attacker can induce an out-of-bounds heap read without requiring prior privileges. This memory disclosure enables the retrieval of process memory layouts and pointers, effectively weakening ASLR and lowering the barrier for subsequent exploit chains.
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).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.2 | N/A | 8.2 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | None | N/A | None |
| Availability Impact | Low | N/A | Low |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
An attacker could get secret values such as cryptographic keys, PII, memory addresses, or other information that could be used in additional attacks.
Confidentiality
Technical Impact: Bypass Protection Mechanism
Out-of-bounds memory could contain memory addresses or other information that can be used to bypass ASLR and other protection mechanisms in order to improve the reliability of exploiting a separate weakness for code execution.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
An attacker could cause a segmentation fault or crash by causing memory to be read outside of the bounds of the buffer. This is especially likely when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string.
Other
Technical Impact: Varies by Context
The read operation could produce other undefined or unexpected results.
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