CVE-2026-45803

A security vulnerability has been identified in GitHub CLI that could allow terminal escape sequence injection when users view GitHub Actions workflow logs using gh run view --log or gh run view --log-failed.

Details

The vulnerability stems from the way GitHub CLI handles raw Actions log output. The gh run view --log and gh run view --log-failed commands stream workflow log lines to stdout or the configured pager without sanitizing terminal control sequences. An attacker who can influence GitHub Actions log content, for example via a PR triggered workflow, can embed escape sequences that are replayed in the user's terminal when they inspect the run.

Depending on the victim's terminal emulator, injected sequences could change the window title, manipulate on screen content, or in some terminal emulators (such as screen) potentially execute arbitrary commands.

In 2.92.0, GitHub CLI sanitizes terminal control sequences in Actions log output before writing to the terminal.

PoC

Create a workflow that emits terminal escape sequences in its log output:

name: Escape Sequence PoC

on:
  workflow_dispatch:

jobs:
  emit-escape-sequences:
    runs-on: ubuntu-latest
    steps:
      - name: Emit terminal escape sequences
        run: |
          # OSC title set
          printf 'ESCAPE_MARKER_START \033]0;HIJACKED_TITLE\007 ESCAPE_MARKER_END\n'
          # CSI color
          printf 'ESCAPE_MARKER_START \033[31mRED_TEXT\033[0m ESCAPE_MARKER_END\n'
          # Screen title set (enables command execution in screen terminal)
          printf 'ESCAPE_MARKER_START \033k;malicious command;\033\\ ESCAPE_MARKER_END\n'

Then trigger the workflow and view its logs:

gh workflow run 'Escape Sequence PoC'
gh run view <run_id> --log

On vulnerable versions, the raw ESC bytes (0x1b) are passed through to the terminal unsanitized. On 2.92.0 and later, escape sequences are stripped and only the safe visible text is displayed.

Remediation and Mitigation

1. Upgrade gh to 2.92.0
2. Pipe log output through a sanitizer (e.g., gh run view --log | cat -v) as a workaround on older versions
3. Exercise caution when viewing logs from untrusted workflow runs

An attacker who can control GitHub Actions workflow output can inject terminal escape sequences into a maintainer's terminal session when they inspect the run with gh run view --log or gh run view --log-failed. The practical impact depends on the victim's terminal emulator.

CVE-2026-45803 has a CVSS score of 3.5 (Low). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.92.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-45803? CVE-2026-45803 is a low-severity security vulnerability in github.com/cli/cli/v2 (go), affecting versions < 2.92.0. It is fixed in 2.92.0.
2. How severe is CVE-2026-45803? CVE-2026-45803 has a CVSS score of 3.5 (Low). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2026-45803?
   • github.com/cli/cli/v2 (go) (versions < 2.92.0)
   • github.com/cli/cli (go) (versions >= 1.6.0, <= 1.14.0)
4. Is there a fix for CVE-2026-45803? Yes. CVE-2026-45803 is fixed in 2.92.0. Upgrade to this version or later.
5. Is CVE-2026-45803 exploitable, and should I be worried? Whether CVE-2026-45803 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-45803 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-45803? Upgrade github.com/cli/cli/v2 to 2.92.0 or later.