CVE-2026-41253

Description

In iTerm2 through 3.6.9, displaying a .txt file can cause code execution via DCS 2000p and OSC 135 data, if the working directory contains a malicious file whose name is valid output from the conductor encoding path, such as a pathname with an initial ace/c+ substring, aka "hypothetical in-band signaling abuse." This occurs because iTerm2 accepts the SSH conductor protocol from terminal output that does not originate from a legitimate conductor session.

CVSS v3.1 Score

6.9

MEDIUM

CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L

EPSS — Exploit Prediction

0.0001

Probability of exploitation

0.00%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-829 CWE-829

References

Other References

https://blog.calif.io/p/mad-bugs-even-cat-readmetxt-is-not https://github.com/gnachman/iTerm2/commit/a9e745993c2e2cbb30b884a16617cd5495899f86 https://iterm2.com/downloads.html https://news.ycombinator.com/item?id=47809190

Frequently Asked Questions

What is CVE-2026-41253? +

In iTerm2 through 3.6.9, displaying a .txt file can cause code execution via DCS 2000p and OSC 135 data, if the working directory contains a malicious file whose name is valid output from the conductor encoding path, such as a pathname with an initial ace/c+ substring, aka "hypothetical in-band signaling abuse." This occurs because iTerm2 accepts the SSH conductor protocol from terminal output that does not originate from a legitimate conductor session. It has a CVSS v3.1 base score of 6.9 (MEDIUM).

How severe is CVE-2026-41253? +

CVE-2026-41253 has a CVSS v3.1 score of 6.9 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0001, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-41253? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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