CVE
fulgur: Unbounded string-set value accumulation causes memory/CPU exhaustion (denial of service)
Affects fulgur 0.4.4 up to 0.29.0 when rendering untrusted HTML/CSS with string-set rules whose values come from content(text), attr(), or CSS string literals. Fixed in 0.29.0.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 0.29.0
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 0.29.0.
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 25/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Unclear
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
fulgur, a tool that converts HTML/CSS to PDF, can be made to exhaust memory and CPU when it processes a crafted document, causing a denial of service. An attacker can reach it remotely over the network without logging in, simply by submitting a malicious document for conversion.
Read the original description
fulgur converts untrusted HTML/CSS into PDF, commonly on a server that processes input supplied by many tenants. From version 0.4.4 to before version 0.29.0, the CSS string-set named-string values resolved from a document were accumulated per element with no memory budget, letting a small crafted document amplify into large retained memory (and the CPU to copy it) — results in a denial of service. This issue has been patched in version 0.29.0.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure17/25No login or user action needed, reachable over the network without a login · Unknown: Advisories don't say whether default setups are affected
- Reach?/20Unknown. No tracked technology or package matched
- Severity7.5/10CVSS 7.5
- No patch0/5No signal
What would change the score
- Would score about 70 if added to CISA KEV
- Would score about 65 if CISA's SSVC rates exploitation active
- Would score about 30 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: 0.29.0.
Workaround: Validate or constrain untrusted CSS before passing HTML to fulgur, and bound the size and element count of accepted input.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-68539 (fulgur: Unbounded string-set value accumulation causes memory/CPU exhaustion (denial of service)), using the cve.now data below.
Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.
What cve.now has for CVE-2026-68539 (entry last updated 2026-11-11):
Affected:
- fulgur-rs fulgur: from 0.4.4, fixed in 0.29.0
Fixed versions: 0.29.0.
Conditions (all must be true for the bug to be hit):
- Rendering untrusted HTML/CSS with string-set rules whose values come from content(text), attr(), or CSS string literals, with a large value matched by many elements. (source: https://github.com/fulgur-rs/fulgur/security/advisories/GHSA-vw2v-g4x7-xcqg)
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: network access, no login, no user action.
Workaround: Validate or constrain untrusted CSS before passing HTML to fulgur, and bound the size and element count of accepted input. (source: https://github.com/fulgur-rs/fulgur/security/advisories/GHSA-vw2v-g4x7-xcqg)
CISA KEV: CVE-2026-68539 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-68539 only. If you also check another CVE, look up its own KEV status; never assume it from this one.
How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.
Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/fulgur-rs/fulgur/security/advisories/GHSA-vw2v-g4x7-xcqg
- https://github.com/fulgur-rs/fulgur/pull/582
- https://github.com/fulgur-rs/fulgur/pull/584
- https://github.com/fulgur-rs/fulgur/commit/1c4cdad003daef7c9dc6ef1362c50bcfaac13ea9
- https://github.com/fulgur-rs/fulgur/commit/9248fbfd91a2ba8fc3dbd9e44ba681f52ed1ecd0
- https://github.com/fulgur-rs/fulgur/releases/tag/v0.29.0
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.
Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.
Entry: https://cve.now/CVE-2026-68539
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-68539"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- fulgur-rs fulgur
From 0.4.4 · fixed in 0.29.0
Evidence 7
Vendor advisory · 1
Establishes: Affected and fixed versions.
- Advisory
Other links · 5
- Repository
- Repository
- Repository
- Repository
- Repository
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-68539
Is CVE-2026-68539 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
fulgur keeps every string-set value it resolves, so a small crafted document with a large string-set value matched by many elements can make it store and copy a very large amount of text. This uses up memory and CPU, which is a denial of service.Source: github.com
Which versions are affected by CVE-2026-68539?
fulgur: from 0.4.4 before 0.29.0.Source: cve.now feed data
Am I affected, and how do I check?
Versions from 0.4.4 up to, but not including, 0.29.0 are affected. The exposure depends on the document: it needs string-set rules whose values come from content(text), attr(), or CSS string literals, and the page must be rendered by fulgur. Check your installed fulgur version in your dependency manifest or lock file, and check whether your templates use string-set.Source: github.com
How do I fix CVE-2026-68539?
Upgrade fulgur to 0.29.0 or later. The advisory says to upgrade to 0.29.0 or later.Source: github.com