GNU cflow through 1.6 has a heap-based buffer over-read in the nexttoken function in parser.c.
- Published
- Sep 9, 2019
- Updated
- Jun 16, 2026
- EPSS
- 1.1% · 65th percentile
- CWE
- CWE-125
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Report tools
Action score
26
Monitor
Low priority for now.
- CVSS
- 26 / 40 · 6.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 1.1%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| gnu | cflow | cpe:2.3:a:gnu:cflow |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- gnu cflowup to 1.6 inclusive
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | cflow | before 1:1.6-6 | 1:1.6-6 |
| openSUSE:Tumbleweed | cflow | before 1.7-1.1 | 1.7-1.1 |
Same product
gnu: all recordsOther highest-scoring records for the same primary product.
- CVE-2023-2789GNU cflow parser.c parse_variable_declaration denial of service30Monitor
- CVE-2019-16165GNU cflow through 1.6 has a use-after-free in the reference function in parser.c.26Monitor
- CVE-2020-23856Use-after-Free vulnerability in cflow 1.6 in the void call(char *name, int line) function at src/parser.c, which could cause a denial of ser22Monitor
- CVE-2025-8736GNU cflow Lexer c.c yylex buffer overflow7Monitor
- CVE-2025-8735GNU cflow Lexer c.c yylex null pointer dereference7Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:cflow | 1:1.6-6 · Debian:12 | Package registry (OSV) |
| opensuse:cflow | 1.7-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- A user must open a link or visit a page.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-125 · Out-of-bounds ReadCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
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References
Vendor advisories and official records. Exploit/PoC links are deliberately left out.