An issue was discovered in Botan 1.11.32 through 2.x before 2.6.0. An off-by-one error when processing malformed TLS-CBC ciphertext could cause the receiving side to include in the HMAC computation exactly 64K bytes of data following the record buffer, aka an over-read. The MAC comparison will subsequently fail and the connection will be closed. This could be used for denial of service. No information leak occurs.
Conclusion & alert: CVE-2018-9860 is rated Moderate Risk (50.8/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.38%). Mandatory action: Review affected assets and schedule remediation.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-05-26 | 0.50% | 0.38% | -0.11% |
| 2 | 2025-11-21 | 0.38% | 0.50% | +0.11% |
| 3 | 2025-11-18 | — | 0.38% | — |
Full EPSS history (9 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 7.5 | 3.0 | HIGH |
|
3.9 | 3.6 | [email protected] |
| 5.0 | 2.0 | MEDIUM |
|
10.0 | 2.9 | [email protected] |
| vendor | priority | summary | link |
|---|---|---|---|
alpine
|
high | CVE-2018-9860: 1 source package rows (botan); 12 state rows across 8 repos (3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, edge-main); fixed 8, open 4. | https://security.alpinelinux.org/vuln/CVE-2018-9860 |
debian
|
not yet assigned | CVE-2018-9860 not yet assigned priority: Debian including 1 source packages (botan), 3 status rows across 3 suites (bookworm, bullseye, trixie): resolved 3. | https://security-tracker.debian.org/tracker/CVE-2018-9860 |
ubuntu
|
medium | CVE-2018-9860 medium priority: Ubuntu including 2 source packages (botan, botan1.10), 40 status rows across 20 suites (artful, bionic, cosmic, disco, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 17, not-affected 17, ignored 3, needed 1, needs-triage 1, released 1. | https://ubuntu.com/security/CVE-2018-9860 |
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| botan_project | botan | >= 1.11.32, < 2.6.0 | cpe:2.3:a:botan_project:botan:*:*:*:*:*:*:*:* |
| URL | Tags |
|---|---|
| https://botan.randombit.net/security.html | Vendor Advisory |
| https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=7434 | Issue Tracking |