CVE-2025-13151Network attack vector

Application crash via one-byte stack buffer overflow

Published Jan 7, 2026 · Updated Jan 7, 2026

Stack-based buffer overflow in GNU libtasn1 4.20.0 and earlier allows attackers to crash applications processing crafted ASN.1 data. In asn1_expand_octet_string in decoding.c, unbounded strcpy and strcat calls join two 64-character names, a dot, and a terminator in a stack buffer that lacks space for the final byte. Exploitation requires an application to call this function with maximum-length definition and element names; definitions normally reside in application code, limiting attacker control.

CVSS severity7.5
High
EPSS probability1.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in GNU libtasn1 4.20.0 and earlier allows attackers to crash applications processing crafted ASN.1 data. In asn1_expand_octet_string in decoding.c, unbounded strcpy and strcat calls join two 64-character names, a dot, and a terminator in a stack buffer that lacks space for the final byte. Exploitation requires an application to call this function with maximum-length definition and element names; definitions normally reside in application code, limiting attacker control.

The record

CVE
CVE-2025-13151
Published
Jan 7, 2026
Updated
Jan 7, 2026
Vendor
The GnuPG Project
Product
libtasn1
Classifications
CWE-787, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 7, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=4.20.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The GnuPG Project · libtasn1version=0 <=4.20.0

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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