Ubuntu USN-8830-1 Fixes phpseclib Vulnerabilities
Tech GuruQuick Answer
USN-8830-1 updates Ubuntu's phpseclib packages for two timing-information leaks and an ASN.1 parsing denial of service. Applications can also bundle phpseclib through Composer. Updating Ubuntu's php-phpseclib package does not prove those separate application copies are fixed.
Confirm Scope And Apply The Supported Fix
Next step: Find which dependency each PHP application loads, record its origin, and update through that package or application's supported channel. Restart relevant long-running workers when needed to load the new code.
Last verified: 2026-09-28 UTC. Recheck the authoritative advisory and supported distribution channel before changing production.
Scope And Authority
| Product scope | phpseclib vulnerabilities on Ubuntu 26.04 LTS (resolute), Ubuntu 24.04 LTS (noble), Ubuntu 22.04 LTS (jammy), Ubuntu 20.04 ESM (focal), Ubuntu 18.04 ESM (bionic), Ubuntu 16.04 ESM (xenial) |
|---|---|
| Advisory | USN-8830-1 |
| CVEs | CVE-2026-32935, CVE-2026-40194, CVE-2026-44167 |
| Authoritative release date | 2026-09-28 13:56:03.541713 UTC |
| Authority revision date | No separate material revision date is stated by Ubuntu; verified against the first-party notice API. |
| Affected versions | The Ubuntu releases and source packages enumerated in USN-8830-1: Ubuntu 26.04 LTS (resolute), Ubuntu 24.04 LTS (noble), Ubuntu 22.04 LTS (jammy), Ubuntu 20.04 ESM (focal), Ubuntu 18.04 ESM (bionic), Ubuntu 16.04 ESM (xenial). |
| Fixed version | bionic: php-phpseclib 2.0.9-1ubuntu0.1~esm3 / focal: php-phpseclib 2.0.23-2ubuntu0.1~esm3 / jammy: php-phpseclib 2.0.36-1ubuntu0.1~esm3 / noble: php-phpseclib 2.0.47-1ubuntu0.1~esm1 / resolute: php-phpseclib 2.0.51-1ubuntu0.1~esm1 / xenial: php-phpseclib 2.0.1-1ubuntu0.1~esm1 |
| CVSS base score | Not provided by the authority |
| CVSS severity | Not provided by the authority |
| Exploitation status | Not stated by the authority; no exploitation claim is inferred. |
What Changed
CVE-2026-32935 concerns AES-CBC padding timing; CVE-2026-40194 concerns SSH packet-MAC comparison timing; CVE-2026-44167 concerns oversized ASN.1 object identifiers. Different code paths have different exposure, so check the features the application uses rather than treating a successful web response as complete validation.
What To Validate Now
- Inventory. Record the Ubuntu release, enabled repositories, installed binary packages (including php-phpseclib), running consumers, and service owner. Check bundled application copies and container images separately.
- Establish applicability. Compare installed binary packages with USN-8830-1's release-specific package table. The source-package builds summarized above identify the advisory's source release; they are not literal package-install commands.
- Remediate. Follow Canonical's current update instructions for the affected binary packages on this Ubuntu release. Confirm security or Pro/ESM repository access as applicable. Do not install a source-package name merely because it appears in the summary table.
- Validate. Confirm the loaded dependency and test the application's actual cryptographic, SSH/SFTP, or parsing workflows. Check expected rejection of invalid input with isolated fixtures. Preserve host-key and integrity checks; disabling them is not an acceptable way to make an updated connection work.
- Retain evidence. Preserve asset and owner identifiers, the applicability decision, before-and-after versions, change approval, installation output, validation results, and any exception or rollback record.
Operational Cautions
Some listed fixes are delivered through Ubuntu Pro or ESM. Confirm entitlement and repository state before the change, use the exact supported release stream, and test dependent services, clusters, and rollback. Severity alone is not evidence of exploitation.
Evidence To Retain
- Exact product, release stream, package or application version, enabled feature, environment, and accountable owner.
- UTC timestamps, authority revision, approved change record, installer or package-manager output, and resulting version.
- Relevant logs and monitoring evidence, test results, exceptions, compensating controls, and rollback decisions.
Related TechGeeks Resources
Authoritative References
Correction policy: If the authority changes affected versions, fixed versions, severity, exploitation information, mitigations, or required action, TechGeeks will update this notice and its verification date.
