CVE-2026-4833

Orc discount Markdown markdown.c compile recursion

No known exploitation. EPSS puts it in the 6th percentile. No fix published yet.

CVSS 3.13.3Low EPSS percentile6th0.2% chance in 30 days CISA KEVNot listedNo confirmed exploitation
No public exploit known FixNone yetNo fix or workaround published

Published 2026-03-26Updated 2026-04-29Sources: CVE.org, NVD

NVD CVE.org

What to do

No fixed build or workaround is published yet. Limit exposure and watch for a patch.

Orc discountAffected: 3.0.1.0Upgrade to: not statedAffected: 3.0.1.1Upgrade to: not statedAffected: 3.0.1.2Upgrade to: not statedStated by: CVE record

Versions as the sources state them. Full version matrix after sign-in

Steps

Written by AI from the record

Check whether your systems use discount, and identify the installed version.
If it is version 3.0.1.2 or earlier, prevent untrusted local users or automated jobs from submitting Markdown files with deeply nested blockquotes.
No fixed version has been published; check the project’s releases or maintainer guidance before upgrading.
Test Markdown-processing jobs after applying any future update and watch for crashes.

May need vendor or contractor work

Check it yourselfA free OpenVAS check exists for this CVE. Run it against your hosts.Is your organisation exposed?Request an assessment to establish which checks fit your systems.

What it is

From the CVE record

A weakness has been identified in Orc discount up to 3.0.1.2. This issue affects the function compile of the file markdown.c of the component Markdown Handler. This manipulation causes uncontrolled recursion. The attack is restricted to local execution. The exploit has been made available to the public and could be used for attacks. The project maintainer confirms: "[I]f you feed it an infinitely deep blockquote input it will crash. (...) [T]his is a duplicate of an old bug that I've been working on."

In plain language

Written by AI from the record

This can crash discount versions up to 3.0.1.2 when someone with local access processes a specially crafted Markdown file; most small businesses should schedule an update review rather than treat it as an emergency.

Local low-complexity denial of service in discount’s Markdown Handler: infinitely nested blockquotes trigger uncontrolled recursion in markdown.c and can crash the process.

If you're affected

Markdown processing crash
Service interruption
Failed document generation

What is it

A flaw in discount can make it keep following an excessively deep chain of quoted text until the program stops working. It is like giving a clerk a stack of folders nested inside folders so deep that they cannot finish the task and the service counter closes.

Who is affected

This matters to you if you use or run discount to process Markdown documents. It is only a risk when someone or something with local access can supply Markdown content to the affected processing feature.

How urgent is it

An attacker would need local access and a crafted Markdown input to cause a crash, and there is no confirmed active exploitation. Treat this as an amber maintenance issue: restrict who can submit Markdown and plan remediation while a vendor fix is unavailable.

What to do — in detail

Confirm whether discount is installed and whether the deployed version is 3.0.1.2 or earlier. Review local workflows, build jobs, imports, and applications that pass user-controlled Markdown into discount; test whether deeply nested blockquotes can reach the Markdown Handler.

There is currently no published fixed version or supported branch target. Do not assume that a newer package version resolves CVE-2026-4833 until the maintainer release notes or advisory explicitly confirms it.

If patching is delayed, reject or limit excessively nested blockquotes before invoking discount, and limit access to systems or jobs that process untrusted Markdown. Monitor application and job logs for recursion failures, crashes, restarts, or failed Markdown-processing tasks. This CVE is not in CISA KEV, so no CISA remediation due date applies.

Technical context

CVSS 3.3 (Low): AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L. The reported weakness is uncontrolled recursion (CWE-674), with CWE-404 also listed, in the compile function of markdown.c in the Markdown Handler; the impact is availability loss through a process crash. CISA KEV does not list this CVE, and no public exploit code is on record. EPSS is 0.1% (2nd percentile) with a flat trend; this is a predicted likelihood, not evidence of exploitation. Press attention is rising but does not establish exploitation.

This is a general assessment based on public vulnerability data. It does not account for your specific infrastructure — when in doubt, consult a security specialist.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS6th

CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

No public exploit or proof of concept found in the sources we track.

EPSS

0.2% chance of exploitation activity in the next 30 days, which ranks it in the 6th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

5 events over 176 days, from the signal feeds we watch.

2026-09-18OpenVAS check added
2026-04-29Record updated
2026-03-26Publishedweakness classified, att&ck mapped

Affected products

Orc
- discount

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

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

Scored 3.3 by NVD.

How it is reached

Attack Vector LocalRequires local access to the vulnerable system (e.g. local login, malicious file)
Attack Complexity LowNo special conditions — the attack can be reliably reproduced
Privileges Required LowRequires basic user-level privileges
User Interaction NoneNo user interaction needed — fully automated exploitation