CVE-2026-9669
Description
A flaw was found in Python's bz2.BZ2Decompressor component. An attacker could provide specially crafted input that, when processed by an application reusing a decompressor object after an error, could lead to out-of-bounds writes in memory. This memory corruption could cause the application to crash, resulting in a Denial of Service (DoS).
Statement
This Moderate-impact flaw in Python's bz2.BZ2Decompressor component affects Red Hat Enterprise Linux 8. It allows an attacker to trigger a denial of service by providing specially crafted compressed data. Exploitation requires an application to reuse a BZ2Decompressor object after a decompression error, leading to out-of-bounds writes and a crash.
Mitigation
Applications processing untrusted BZ2 compressed data should avoid reusing `bz2.BZ2Decompressor` objects after a decompression error. Instead, a new `bz2.BZ2Decompressor` instance should be created for each new decompression attempt or after an error occurs. This prevents the decompressor from resuming from an invalid internal state.
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 | 5.9 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | High | N/A | N/A |
| Privileges Required | None | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/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.
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