CVE-2026-8149
GCM chunking can lead to bad tag exception on decryption
- Published
- Updated
- Reserved
- Assigned by
- bcorg
Description
A vulnerability in Legion of the Bouncy Castle Inc. BC-LTS bcprov-lts8on on X86_64, AVX, AVX-512f, Linux, Legion of the Bouncy Castle Inc. BC-FJA bc-fips on Linux, X86_64, AVX, AVX-512f. This vulnerability is associated with program files gcm128w, gcm512w, gcm128w.C, gcm512w.C. This issue affects BC-LTS: from 2.73.0 before 2.73.11; BC-FJA: from 2.1.0 before 2.1.3.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| bcorgCNA (assigner) | 4.0 | Medium5.1 | CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/S:N/RE:M/U:Amber |
| NVDNVD · Awaiting Analysis | 4.0 | Medium5.1 | CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/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:N/AU:X/R:X/V:X/RE:M/U:Amber |
- EPSS (exploitation in 30 days)
- 0.16% · top 95% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.1.
Weakness
Affected products
Legion of the Bouncy Castle Inc. · BC-LTS
- affected 2.73.0 – < 2.73.11
Legion of the Bouncy Castle Inc. · BC-FJA
- affected 2.1.0 – < 2.1.3
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Mavenorg.bouncycastle:bcprov-lts8onGHSA-mx76-r943-rf8g (opens in a new tab)
What to do
Workaround: If possible pass whole message to GCM via doFinal(..) for decryption. Issue only occurs when decryption is chunked at certain boundaries.
References (1)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-mx76-r943-rf8g (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-8149)Record last updated .