CVE-2026-6986
Cesanta Mongoose GCM Authentication Tag tls_aes128.c mg_aes_gcm_decrypt signature verification
A security vulnerability has been detected in Cesanta Mongoose up to 7.20. This issue affects the function mg_aes_gcm_decrypt of the file /src/tls_aes128.c of the component GCM Authentication Tag Handler. Such manipulation leads to improper verification of cryptographic signature. The attack may be performed from remote. A high complexity level is associated with this attack. The exploitability is assessed as difficult. The exploit has been disclosed publicly and may be used. Upgrading to version 7.21 is capable of addressing this issue. It is advisable to upgrade the affected component. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
6.3
Cesanta Mongoose GCM Authentication Tag tls_aes128.c mg_aes_gcm_decrypt signature verification
A security vulnerability has been detected in Cesanta Mongoose up to 7.20. This issue affects the function mg_aes_gcm_decrypt of the file /src/tls_aes128.c of the component GCM Authentication Tag Handler. Such manipulation leads to improper verification of cryptographic signature. The attack may be performed from remote. A high complexity level is associated with this attack. The exploitability is assessed as difficult. The exploit has been disclosed publicly and may be used. Upgrading to version 7.21 is capable of addressing this issue. It is advisable to upgrade the affected component. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.
- Record
CVE-2026-6986- CVSS 4.0
- 6.3 Medium
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P - CVSS 3.1
- 3.7 Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:C - CVSS 3.0
- 3.7 Low
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:C - CVSS 2.0
- 2.6
AV:N/AC:H/Au:N/C:N/I:P/A:N/E:POC/RL:OF/RC:C - Weakness
- CWE-347, CWE-345
- Updated
- 2026-11-02
EUVDEUVD-2026-25662
6.3
A security vulnerability has been detected in Cesanta Mongoose up to 7.20. This issue affects the function mg_aes_gcm_decrypt of the file /src/tls_aes128.c of the component GCM Authentication Tag Handler. Such manipulation leads to improper verification of cryptographic signature. The attack may be performed from remote. A high complexity level is associated with this attack. The exploitability is assessed as difficult. The exploit has been disclosed publicly and may be used. Upgrading to version 7.21 is capable of addressing this issue. It is advisable to upgrade the affected component. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.
- Record
EUVD-2026-25662- CVSS 4.0
- 6.3 Medium
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-p5j9-fjff-qrmr
2.9
A security vulnerability has been detected in Cesanta Mongoose up to 7.20. This issue affects the...
A security vulnerability has been detected in Cesanta Mongoose up to 7.20. This issue affects the function mg_aes_gcm_decrypt of the file /src/tls_aes128.c of the component GCM Authentication Tag Handler. Such manipulation leads to improper verification of cryptographic signature. The attack may be performed from remote. A high complexity level is associated with this attack. The exploitability is assessed as difficult. The exploit has been disclosed publicly and may be used. Upgrading to version 7.21 is capable of addressing this issue. It is advisable to upgrade the affected component. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.
- Record
GHSA-p5j9-fjff-qrmr- CVSS 4.0
- 2.9 Low
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/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
- 3.7 Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N - Weakness
- CWE-345
- Updated
- 2026-11-02
NVD
2.9
A security vulnerability has been detected in Cesanta Mongoose up to 7.20. This issue affects the function mg_aes_gcm_decrypt of the file /src/tls_aes128.c of the component GCM Authentication Tag Handler. Such manipulation leads to improper verification of cryptographic signature. The attack may be performed from remote. A high complexity level is associated with this attack. The exploitability is assessed as difficult. The exploit has been disclosed publicly and may be used. Upgrading to version 7.21 is capable of addressing this issue. It is advisable to upgrade the affected component. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.
- Record
CVE-2026-6986- CVSS 4.0
- 2.9 Low
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/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
- 3.7 Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N - CVSS 2.0
- 2.6 Low
AV:N/AC:H/Au:N/C:N/I:P/A:N - Weakness
- CWE-345, CWE-347
- Updated
- 2026-11-02
OSV
2.9
Cesanta Mongoose GCM Authentication Tag tls_aes128.c mg_aes_gcm_decrypt signature verification
A security vulnerability has been detected in Cesanta Mongoose up to 7.20. This issue affects the function mg_aes_gcm_decrypt of the file /src/tls_aes128.c of the component GCM Authentication Tag Handler. Such manipulation leads to improper verification of cryptographic signature. The attack may be performed from remote. A high complexity level is associated with this attack. The exploitability is assessed as difficult. The exploit has been disclosed publicly and may be used. Upgrading to version 7.21 is capable of addressing this issue. It is advisable to upgrade the affected component. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.
- Record
CVE-2026-6986- CVSS 4.0
- 2.9 Low
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P - Weakness
- CWE-345, CWE-347
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2026-6986
2.9
A security vulnerability has been detected in Cesanta Mongoose up to 7.20. This issue affects the function mg_aes_gcm_decrypt of the file /src/tls_aes128.c of the component GCM Authentication Tag Handler. Such manipulation leads to improper verification of cryptographic signature. The attack may be performed from remote. A high complexity level is associated with this attack. The exploitability is assessed as difficult. The exploit has been disclosed publicly and may be used. Upgrading to version 7.21 is capable of addressing this issue. It is advisable to upgrade the affected component. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.
- Record
DEBIAN-CVE-2026-6986- CVSS 4.0
- 2.9 Low
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/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 - Updated
- 2026-11-02
OSVJLSEC-2026-373
2.9
A security vulnerability has been detected in Cesanta Mongoose up to 7.20. This issue affects the function mg_aes_gcm_decrypt of the file /src/tls_aes128.c of the component GCM Authentication Tag Handler. Such manipulation leads to improper verification of cryptographic signature. The attack may be performed from remote. A high complexity level is associated with this attack. The exploitability is assessed as difficult. The exploit has been disclosed publicly and may be used. Upgrading to version 7.21 is capable of addressing this issue. It is advisable to upgrade the affected component. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.
- Record
JLSEC-2026-373- CVSS 4.0
- 2.9 Low
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/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 2.0
- 2.6 Low
AV:N/AC:H/Au:N/C:N/I:P/A:N - CVSS 3.1
- 3.7 Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N - Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-6986
2.9
A security vulnerability has been detected in Cesanta Mongoose up to 7.20. This issue affects the function mg_aes_gcm_decrypt of the file /src/tls_aes128.c of the component GCM Authentication Tag Handler. Such manipulation leads to improper verification of cryptographic signature. The attack may be performed from remote. A high complexity level is associated with this attack. The exploitability is assessed as difficult. The exploit has been disclosed publicly and may be used. Upgrading to version 7.21 is capable of addressing this issue. It is advisable to upgrade the affected component. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.
- Record
UBUNTU-CVE-2026-6986- CVSS 4.0
- 2.9 Low
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P - CVSS 3.1
- 3.7 Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
swupdateDebian:12 |
All versions, plus listed versions 2022.12+dfsg-42022.12+dfsg-4+deb12u12022.12+dfsg-4+deb12u1~bpo11+12022.12+dfsg-4+deb12u22022.12+dfsg-4+deb12u3 Show 45 moreShow less2023.05+dfsg-12023.05+dfsg-22023.05+dfsg-2~bpo12+12023.05+dfsg-32023.05+dfsg-42023.05+dfsg-52023.05+dfsg-5~bpo12+12023.12+dfsg-12023.12+dfsg-1~bpo12+12023.12.1+dfsg-12023.12.1+dfsg-1~bpo12+12023.12.1+dfsg-22023.12.1+dfsg-2~bpo12+12024.05+dfsg-12024.05.2+dfsg-12024.05.2+dfsg-22024.05.2+dfsg-2~bpo12+12024.12+dfsg-12024.12+dfsg-22024.12+dfsg-2~bpo12+12024.12.1+dfsg-12024.12.1+dfsg-1~bpo12+12024.12.1+dfsg-22024.12.1+dfsg-32024.12.1+dfsg-3~bpo12+12025.05+dfsg-12025.05+dfsg-22025.05+dfsg-2~bpo13+12025.05+dfsg-32025.05+dfsg-3~bpo13+12025.12+dfsg-12025.12+dfsg-102025.12+dfsg-10~bpo13+12025.12+dfsg-10~bpo13+22025.12+dfsg-22025.12+dfsg-2~bpo13+12025.12+dfsg-32025.12+dfsg-42025.12+dfsg-52025.12+dfsg-62025.12+dfsg-72025.12+dfsg-7~bpo13+12025.12+dfsg-82025.12+dfsg-92026.05+dfsg-1 |
None known |
swupdateDebian:13 |
All versions, plus listed versions 2024.12.1+dfsg-32024.12.1+dfsg-3+deb13u12024.12.1+dfsg-3+deb13u22025.05+dfsg-12025.05+dfsg-2 Show 27 moreShow less2025.05+dfsg-2~bpo13+12025.05+dfsg-32025.05+dfsg-3~bpo13+12025.12+dfsg-12025.12+dfsg-102025.12+dfsg-10~bpo13+12025.12+dfsg-10~bpo13+22025.12+dfsg-22025.12+dfsg-2~bpo13+12025.12+dfsg-32025.12+dfsg-42025.12+dfsg-52025.12+dfsg-62025.12+dfsg-72025.12+dfsg-7~bpo13+12025.12+dfsg-82025.12+dfsg-92026.05+dfsg-12026.05+dfsg-22026.05+dfsg-32026.05+dfsg-3~bpo13+12026.05+dfsg-42026.05.1+dfsg-12026.05.1+dfsg-1~bpo13+12026.05.1+git20261001+dfsg-12026.05.1+git20261001+dfsg-22026.05.1+git20261001+dfsg-2~bpo13+1 |
None known |
swupdateDebian:14 |
before 2025.12+dfsg-10, plus listed versions 2024.12.1+dfsg-32025.05+dfsg-12025.05+dfsg-22025.05+dfsg-2~bpo13+12025.05+dfsg-3 Show 14 moreShow less2025.05+dfsg-3~bpo13+12025.12+dfsg-12025.12+dfsg-10~bpo13+12025.12+dfsg-10~bpo13+22025.12+dfsg-22025.12+dfsg-2~bpo13+12025.12+dfsg-32025.12+dfsg-42025.12+dfsg-52025.12+dfsg-62025.12+dfsg-72025.12+dfsg-7~bpo13+12025.12+dfsg-82025.12+dfsg-9 |
2025.12+dfsg-10 |
Mongoose_jllJulia |
before 7.21.0+0 | 7.21.0+0 |
swupdateUbuntu:22.04:LTS |
All versions, plus listed versions 2020.11-22021.04-1.12021.04-22021.04-2build12021.11-1 |
None known |
swupdateUbuntu:24.04:LTS |
All versions, plus listed versions 2023.05+dfsg-32023.05+dfsg-42023.05+dfsg-4build12023.05+dfsg-52023.12+dfsg-12023.12.1+dfsg-1ubuntu12023.12.1+dfsg-1ubuntu42023.12.1+dfsg-1ubuntu5 |
None known |
swupdateUbuntu:25.10 |
All versions, plus listed versions 2024.12.1+dfsg-1build22024.12.1+dfsg-22024.12.1+dfsg-32025.05+dfsg-2ubuntu1 |
None known |
swupdateUbuntu:26.10 |
All versions, plus listed versions 2025.12+dfsg-4ubuntu12026.05+dfsg-3ubuntu22026.05+dfsg-4ubuntu12026.05.1+dfsg-1ubuntu12026.05.1+git20261001+dfsg-1ubuntu1 |
None known |
swupdateUbuntu:26.04:LTS |
All versions, plus listed versions 2025.05+dfsg-2ubuntu12025.05+dfsg-3ubuntu12025.12+dfsg-1ubuntu12025.12+dfsg-2ubuntu12025.12+dfsg-3ubuntu12025.12+dfsg-4ubuntu1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-6986 is a medium vulnerability (CVSS 6.3) in Automattic Mongoose, published April 25, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.22%, the 12th percentile. Fixed in swupdate 2025.12+dfsg-10.
References
Left out here: 9 versions. The JSON record has them.