# CVE-2026-102555: Libsoup: libsoup: heap buffer overflow via uninitialized length in data-uri base64 decoding

> Attackers can cause application crashes or out-of-bounds reads in libsoup by sending crafted data URIs with embedded NUL bytes.

- **Severity:** High 8.2 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 29 Sep 2026
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-105552, DEBIAN-CVE-2026-102555, ECHO-940b-9dd5-9d88, GHSA-vfxx-hcqj-vrh4, ROOT-OS-DEBIAN-13-CVE-2026-102555, UBUNTU-CVE-2026-102555

## What is CVE-2026-102555?

CVE-2026-102555 is a high-severity memory corruption vulnerability in Redhat Enterprise Linux, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A flaw was found in libsoup. The soup_uri_decode_data_uri() function incorrectly treated base64 data-URI payloads as NUL-terminated strings when calling g_base64_decode_inplace(). If the percent-decoded payload contained embedded NUL bytes, the decoded length could remain uninitialized and be used as the size of the returned GBytes. This can lead to an out-of-bounds read or application crash when processing a crafted data URI.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-102555?

It affects 2 products.


Products: Gnome Libsoup, Redhat Enterprise Linux.

## How do I fix CVE-2026-102555?

Apply the vendor's patch.

## Is CVE-2026-102555 being exploited?

There is no known exploitation of CVE-2026-102555 in the wild and no public exploit code.

## Other vulnerabilities in Redhat Enterprise Linux

- [CVE-2026-102556](https://insights.sbomify.com/CVE-2026-102556/): Libsoup: libsoup: heap buffer overflow from websocket pong signal type confusion (high 8.6)
- [CVE-2026-102557](https://insights.sbomify.com/CVE-2026-102557/): Libsoup: libsoup: heap buffer overflow during websocket message reassembly (high 8.6)
- [CVE-2026-102558](https://insights.sbomify.com/CVE-2026-102558/): Libsoup: libsoup: heap buffer overflow during websocket receive-buffer growth (high 8.6)
- [CVE-2026-102559](https://insights.sbomify.com/CVE-2026-102559/): Libsoup: libsoup: heap buffer overflow during websocket client-frame masking (high 8.6)
- [CVE-2026-102560](https://insights.sbomify.com/CVE-2026-102560/): Libsoup: libsoup: heap buffer overflow during outgoing permessage-deflate buffer growth (high 8.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-102555 and fix it if it is affected.

What it is: CVE-2026-102555 is a high-severity memory corruption vulnerability in Redhat Enterprise Linux, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-102555 in the wild and no public exploit code.

Affected product: Redhat Enterprise Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-102555/ (Markdown: https://insights.sbomify.com/CVE-2026-102555/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-102555
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-102555
- OSV: https://osv.dev/vulnerability/CVE-2026-102555

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-102555/
Summaries are generated and may contain mistakes; the official description above is the record.