NVD / CVE Program· CNA VulnCheck

CVE-2026-126049: Gwenhywfar 5.14.2 Use-After-Free via GWEN_TLV_Buffer_To_DB() Nested BER-TLV Parsing

MediumCVSS 5.1 · v4.0—No exploit No fix recorded

Noroxi assessment

Priority: Monitor (action score 20/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.19% (FIRST EPSS).
Physical access to the device is required. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
No fixed version is recorded, but the references include a patch (commit or PR) link.

Low priority for now. See the fix and affected versions sections below.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Gwenhywfar 5.14.2 contains a heap use-after-free vulnerability in GWEN_TLV_Buffer_To_DB() in src/parser/tlv.c, which frees a nested record's GWEN_DB node when parsing of its contents fails but continues processing and adds the freed node to the parent instead of returning. Attackers can supply a constructed BER-TLV record with unparseable contents, such as via a malicious chip card read by libchipcard, to corrupt heap memory.

Memory safety

EUVD-2026-121407

Published: Nov 10, 2026
Updated: Nov 12, 2026
EPSS: 0.1% · 9th percentile
CWE: CWE-416

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 20 / 40 · 5.1 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.1%

CNA vs NVD score

NVD: —
CNA · VulnCheck: 5.1; NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:P/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (VulnCheck). Independent of NVD's CPE analysis and usually ahead of it.

Martin Preuss Gwenhywfar
- 5.14.2 and later · before 5.14.3affected

Same product

martin preuss: all records

Other highest-scoring records for the same primary product.

CVE-2026-126048Gwenhywfar 4.99.8beta before 5.14.2 Stack Buffer Overflow via GWEN_TLV_Buffer_To_DB()
20Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

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.

EPSS, last 120 days

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.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Deus Rexfinder

Not on record for this CVE: variant or chain candidate · public bounty program.

Technical details

Attack conditions

Physical access to the device is required.
No account or password is required.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability

Attack vector: Physical
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: X

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

CVSS:4.0/AV:P/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1free(dev->buf);
2/* ... another thread is still running ... */
3process(dev->buf);

Fixed

1lock(&dev->lock);
2free(dev->buf);
3dev->buf = NULL;
4unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log (1)

Exploit maturity— → noneNov 10, 2026, 6:07 PM UTC

For records you follow, these changes also arrive as notifications. →

References

github.com/aqbanking/gwenhywfar/blob/f5c3f9dc56aa20cab85fd149885474239cf68632/src/parser/tlv.c#L651-L672

Show all references (4 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records