# CVE-2026-54511: @logtape/syslog: syslog log injection via unescaped control characters and unvalidated SD-NAME keys

> Attackers can forge syslog records by injecting control characters or invalid keys when structured data logging is enabled, compromising SIEM integrity.

- **Severity:** High 8.6 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 Aug 2026
- **Updated:** 27 Aug 2026
- **Also known as:** GHSA-8h6h-x5pq-56fq

## What is CVE-2026-54511?

CVE-2026-54511 is a high-severity vulnerability in dahlia logtape, published on 26 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

LogTape is an unobtrusive logging library. Prior to 1.3.11, 2.0.14, and 2.1.5, the @logtape/syslog package's escapeStructuredDataValue() function in packages/syslog/src/syslog.ts does not neutralize C0 control characters from U+0000 through U+001F in structured data values, and formatStructuredData() inserts property keys without validating the RFC 5424 SD-NAME grammar. When includeStructuredData is true, an attacker-controlled newline can terminate an RFC 6587 non-transparent TCP syslog frame and make following bytes appear as a forged RFC 5424 record, while a key containing a closing bracket or other forbidden character can terminate or corrupt the structured-data element. Applications that forward attacker-controlled property values or keys can therefore allow forged records with arbitrary hosts, applications, process identifiers, facilities, or severity levels, undermining downstream collector and SIEM integrity. This issue is fixed in versions 1.3.11, 2.0.14, and 2.1.5.

Weakness: CWE-93 (Improper Neutralization of CRLF Sequences), CWE-117 (Improper Output Neutralization for Logs)

## Which versions are affected by CVE-2026-54511?

6 open source packages ship an affected version, including @logtape/syslog.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@logtape/syslog` | npm | All versions | 1.3.11 |
| `@logtape/syslog` | npm | All versions | 1.3.11 |
| `@logtape/syslog` | npm | From 2.0.0 | 2.0.14 |
| `@logtape/syslog` | npm | From 2.0.0 | 2.0.14 |
| `@logtape/syslog` | npm | From 2.1.0 | 2.1.5 |
| `@logtape/syslog` | npm | From 2.1.0 | 2.1.5 |

## How do I fix CVE-2026-54511?

Upgrade @logtape/syslog to a fixed version for your release line: 1.3.11, 2.0.14 or 2.1.5.

## Is CVE-2026-54511 being exploited?

There is no known exploitation of CVE-2026-54511 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54511 and fix it if it is affected.

What it is: CVE-2026-54511 is a high-severity vulnerability in dahlia logtape, published on 26 Aug 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-2026-54511 in the wild and no public exploit code.

Affected packages and fixed versions:
- @logtape/syslog (npm): affected all versions; fixed in 1.3.11
- @logtape/syslog (npm): affected all versions; fixed in 1.3.11
- @logtape/syslog (npm): affected from 2.0.0; fixed in 2.0.14
- @logtape/syslog (npm): affected from 2.0.0; fixed in 2.0.14
- @logtape/syslog (npm): affected from 2.1.0; fixed in 2.1.5
- @logtape/syslog (npm): affected from 2.1.0; fixed in 2.1.5

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-2026-54511/ (Markdown: https://insights.sbomify.com/CVE-2026-54511/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54511
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54511
- OSV: https://osv.dev/vulnerability/CVE-2026-54511

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-54511/
Summaries are generated and may contain mistakes; the official description above is the record.