EUVD-2026-23834
GHSA-9r7w-j29g-xqx8
CVSS VectorNVD
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
3DescriptionNVD
When sed is invoked with both -i (in-place edit) and --follow-symlinks, the function open_next_file() performs two separate, non-atomic filesystem operations on the same path:
- resolves symlink to its target and stores the resolved path for determining when output is written,
- opens the original symlink path (not the resolved one) to read the file.
Between these two calls there is a race window. If an attacker atomically replaces the symlink with a different target during that window, sed will: read content from the new (attacker-chosen) symlink target and write the processed result to the path recorded in step 1. This can lead to arbitrary file overwrite with attacker-controlled content in the context of the sed process.
This issue was fixed in version 4.10.
AnalysisAI
GNU sed with -i (in-place edit) and --follow-symlinks options is vulnerable to a time-of-check-time-of-use (TOCTOU) race condition that allows local attackers to overwrite arbitrary files with attacker-controlled content. An attacker can atomically replace a symlink target between sed's symlink resolution and file open operations, causing sed to read from an attacker-chosen file while writing output to an unintended location. …
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