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CVE-2026-29013

libcoap Out-of-Bounds Read in OSCORE CBOR Unwrap Handling

8.8 HighFix available

libcoap contains out-of-bounds read vulnerabilities in OSCORE Appendix B.2 CBOR unwrap handling where get_byte_inc() in src/oscore/oscore_cbor.c relies solely on assert() for bounds checking, which is removed in release builds compiled with NDEBUG. Attackers can send crafted CoAP requests with malformed OSCORE options or responses during OSCORE negotiation to trigger out-of-bounds reads during CBOR parsing and potentially cause out-of-bounds reads through integer wraparound in allocation size computation.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
Low
Availability
High

Exploit likelihood

0.30%Up 0.3 points since Apr 18, 2026
90%50%10%1%

What each source reports

CVE List Score used 8.8

libcoap Out-of-Bounds Read in OSCORE CBOR Unwrap Handling

libcoap contains out-of-bounds read vulnerabilities in OSCORE Appendix B.2 CBOR unwrap handling where get_byte_inc() in src/oscore/oscore_cbor.c relies solely on assert() for bounds checking, which is removed in release builds compiled with NDEBUG. Attackers can send crafted CoAP requests with malformed OSCORE options or responses during OSCORE negotiation to trigger out-of-bounds reads during CBOR parsing and potentially cause out-of-bounds reads through integer wraparound in allocation size computation.

Record
CVE-2026-29013
CVSS 4.0
8.8 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-125
Updated
2026-11-02
EUVDEUVD-2026-23535 8.8

libcoap contains out-of-bounds read vulnerabilities in OSCORE Appendix B.2 CBOR unwrap handling where get_byte_inc() in src/oscore/oscore_cbor.c relies solely on assert() for bounds checking, which is removed in release builds compiled with NDEBUG. Attackers can send crafted CoAP requests with malformed OSCORE options or responses during OSCORE negotiation to trigger out-of-bounds reads during CBOR parsing and potentially cause out-of-bounds reads through integer wraparound in allocation size computation.

Record
EUVD-2026-23535
CVSS 4.0
8.8 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:H/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-4vrr-6f8v-98rf 8.8

libcoap contains out-of-bounds read vulnerabilities in OSCORE Appendix B.2 CBOR unwrap handling...

libcoap contains out-of-bounds read vulnerabilities in OSCORE Appendix B.2 CBOR unwrap handling where get_byte_inc() in src/oscore/oscore_cbor.c relies solely on assert() for bounds checking, which is removed in release builds compiled with NDEBUG. Attackers can send crafted CoAP requests with malformed OSCORE options or responses during OSCORE negotiation to trigger out-of-bounds reads during CBOR parsing and potentially cause heap buffer overflow writes through integer wraparound in allocation size computation.

Record
GHSA-4vrr-6f8v-98rf
CVSS 4.0
8.8 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/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
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-125
Updated
2026-11-02
NVD 8.8

libcoap contains out-of-bounds read vulnerabilities in OSCORE Appendix B.2 CBOR unwrap handling where get_byte_inc() in src/oscore/oscore_cbor.c relies solely on assert() for bounds checking, which is removed in release builds compiled with NDEBUG. Attackers can send crafted CoAP requests with malformed OSCORE options or responses during OSCORE negotiation to trigger out-of-bounds reads during CBOR parsing and potentially cause out-of-bounds reads through integer wraparound in allocation size computation.

Record
CVE-2026-29013
CVSS 4.0
8.8 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/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
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-125
Updated
2026-11-02
OSV 8.8

libcoap Out-of-Bounds Read in OSCORE CBOR Unwrap Handling

libcoap contains out-of-bounds read vulnerabilities in OSCORE Appendix B.2 CBOR unwrap handling where get_byte_inc() in src/oscore/oscore_cbor.c relies solely on assert() for bounds checking, which is removed in release builds compiled with NDEBUG. Attackers can send crafted CoAP requests with malformed OSCORE options or responses during OSCORE negotiation to trigger out-of-bounds reads during CBOR parsing and potentially cause out-of-bounds reads through integer wraparound in allocation size computation.

Record
CVE-2026-29013
CVSS 4.0
8.8 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-125
Updated
2026-11-02
OSVDEBIAN-CVE-2026-29013 9.8

libcoap contains out-of-bounds read vulnerabilities in OSCORE Appendix B.2 CBOR unwrap handling where get_byte_inc() in src/oscore/oscore_cbor.c relies solely on assert() for bounds checking, which is removed in release builds compiled with NDEBUG. Attackers can send crafted CoAP requests with malformed OSCORE options or responses during OSCORE negotiation to trigger out-of-bounds reads during CBOR parsing and potentially cause out-of-bounds reads through integer wraparound in allocation size computation.

Record
DEBIAN-CVE-2026-29013
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2026-29013 8.8

libcoap contains out-of-bounds read vulnerabilities in OSCORE Appendix B.2 CBOR unwrap handling where get_byte_inc() in src/oscore/oscore_cbor.c relies solely on assert() for bounds checking, which is removed in release builds compiled with NDEBUG. Attackers can send crafted CoAP requests with malformed OSCORE options or responses during OSCORE negotiation to trigger out-of-bounds reads during CBOR parsing and potentially cause out-of-bounds reads through integer wraparound in allocation size computation.

Record
UBUNTU-CVE-2026-29013
CVSS 4.0
8.8 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:H/SC:N/SI:N/SA:N
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVopenSUSE-SU-2026:10592-1 No score

libcoap-devel-4.3.5b-1.1 on GA media

These are all security issues fixed in the libcoap-devel-4.3.5b-1.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2026:10592-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
libcoap3
Debian:12
All versions, plus listed versions
4.3.1-14.3.1-24.3.3-14.3.4-14.3.4-1.1
Show 5 moreShow less
4.3.4-1.1~exp14.3.5-14.3.5-24.3.5-34.3.5-4
None known
libcoap3
Debian:13
before 4.3.4-1.1+deb13u3, plus listed versions
4.3.4-1.14.3.4-1.1+deb13u14.3.4-1.1+deb13u2
4.3.4-1.1+deb13u3
libcoap3
Debian:14
before 4.3.5-3, plus listed versions
4.3.4-1.14.3.5-14.3.5-2
4.3.5-3
libcoap
Ubuntu:18.04:LTS
All versions, plus listed versions
4.1.2-1
None known
libcoap2
Ubuntu:20.04:LTS
All versions, plus listed versions
4.2.0-24.2.1-1
None known
libcoap2
Ubuntu:22.04:LTS
All versions, plus listed versions
4.2.1-14.2.1-1build1
None known
libcoap3
Ubuntu:22.04:LTS
All versions, plus listed versions
4.3.0-24.3.0-2build1
None known
libcoap3
Ubuntu:24.04:LTS
All versions, plus listed versions
4.3.1-24.3.3-14.3.4-14.3.4-1.1build24.3.4-1.1build34.3.4-1.1build4
None known
libcoap3
Ubuntu:25.10
All versions, plus listed versions
4.3.4-1.1build4
None known
libcoap3
Ubuntu:26.10
All versions, plus listed versions
4.3.5-24.3.5-34.3.5-44.3.5-4ubuntu1
None known
libcoap3
Ubuntu:26.04:LTS
All versions, plus listed versions
4.3.4-1.1build44.3.5-14.3.5-2
None known
libcoap
openSUSE:Tumbleweed
before 4.3.5b-1.1
4.3.5b-1.1

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-29013 is a high vulnerability (CVSS 8.8) in Libcoap, published April 17, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.30%, the 22nd percentile. Fixed in libcoap3 4.3.4-1.1+deb13u3.

References

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