CVE-2026-32935: phpseclib's AES-CBC unpadding susceptible to padding oracle timing attack

Published Mar 19, 2026
·
Updated

Impact Those using AES in CBC mode may be susceptible to a padding oracle timing attack.

Patches https://github.com/phpseclib/phpseclib/commit/ccc21aef71eb170e9bf819b167e67d1fd9e6e788

Workarounds Use AES in CTR, CFB or OFB modes

Other sources

phpseclib is a PHP secure communications library. Projects using versions 0.1.1 through 1.0.26, 2.0.0 through 2.0.51, and 3.0.0 through 3.0.49 are vulnerable to a to padding oracle timing attack when using AES in CBC mode. This issue has been fixed in versions 1.0.27, 2.0.52 and 3.0.50.

— MITRE

phpseclib's AES-CBC unpadding susceptible to padding oracle timing attack

— Packagist

Affected Software

13 affected componentsFixes available
composer/phpseclib/phpseclib<=1.0.26
1.0.27
composer/phpseclib/phpseclib>=2.0.0<=2.0.51
2.0.52
composer/phpseclib/phpseclib>=3.0.0<=3.0.49
3.0.50
phpseclib phpseclib<1.0.27
phpseclib phpseclib>=2.0.0<2.0.52
phpseclib phpseclib>=3.0.0<3.0.50
debian/php-phpseclib
2.0.42-1+deb12u52.0.42-1+deb12u32.0.48-3+deb13u32.0.48-3+deb13u12.0.55-1
debian/php-phpseclib3
3.0.19-1+deb12u63.0.19-1+deb12u43.0.43-2+deb13u33.0.43-2+deb13u13.0.57-1
debian/phpseclib
1.0.20-1+deb12u51.0.20-1+deb12u31.0.23-6+deb13u31.0.23-6+deb13u11.0.30-1
composer/phpseclib/phpseclib>=0.1.1, <=1.0.26
composer/phpseclib/phpseclib>=2.0.0, <=2.0.51
composer/phpseclib/phpseclib>=3.0.0, <=3.0.49
composer/phpseclib/phpseclib>=0.1.1<=1.0.26
1.0.27

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade composer/phpseclib/phpseclib to a version that resolves this vulnerability.

    Fixed in 1.0.27
  2. Upgrade

    Upgrade composer/phpseclib/phpseclib to a version that resolves this vulnerability.

    Fixed in 2.0.52
  3. Upgrade

    Upgrade composer/phpseclib/phpseclib to a version that resolves this vulnerability.

    Fixed in 3.0.50
  4. Upgrade

    Upgrade debian/php-phpseclib to a version that resolves this vulnerability.

    Fixed in 2.0.42-1+deb12u5Fixed in 2.0.42-1+deb12u3Fixed in 2.0.48-3+deb13u3Fixed in 2.0.48-3+deb13u1Fixed in 2.0.55-1
  5. Upgrade

    Upgrade debian/php-phpseclib3 to a version that resolves this vulnerability.

    Fixed in 3.0.19-1+deb12u6Fixed in 3.0.19-1+deb12u4Fixed in 3.0.43-2+deb13u3Fixed in 3.0.43-2+deb13u1Fixed in 3.0.57-1
  6. Upgrade

    Upgrade debian/phpseclib to a version that resolves this vulnerability.

    Fixed in 1.0.20-1+deb12u5Fixed in 1.0.20-1+deb12u3Fixed in 1.0.23-6+deb13u3Fixed in 1.0.23-6+deb13u1Fixed in 1.0.30-1
  7. Upgrade

    Upgrade phpseclib to a version that resolves this vulnerability.

    Fixed in 1.0.27
  8. Upgrade

    Upgrade phpseclib to a version that resolves this vulnerability.

    Fixed in 2.0.52
  9. Upgrade

    Upgrade phpseclib to a version that resolves this vulnerability.

    Fixed in 3.0.50
  10. Configuration

    Use AES in CTR, CFB, or OFB mode instead of CBC mode.

    AES mode = CTR, CFB, or OFB

Event History

Mar 19, 2026
Advisory Published
via GitHub·04:42 PM
Data Sourced
via GitHub·04:42 PM
DescriptionWeaknessAffected Software
Data Sourced
via Packagist·04:42 PM
DescriptionSeverityAffected Software
Mar 20, 2026
CVE Published
via MITRE·02:48 AM
Data Sourced
via MITRE·02:48 AM
DescriptionWeakness
Data Sourced
via NVD·03:16 AM
RemedyDescriptionSeverityWeaknessAffected Software

Frequently Asked Questions

1

What is the severity of CVE-2026-32935?

CVE-2026-32935 is considered a moderate severity vulnerability due to its exploitation via a padding oracle timing attack.

2

How do I fix CVE-2026-32935?

To fix CVE-2026-32935, upgrade phpseclib to version 1.0.27, 2.0.52, or 3.0.50 or later.

3

What vulnerability does CVE-2026-32935 address?

CVE-2026-32935 addresses a susceptibility in phpseclib's AES-CBC unpadding that can be attacked using a padding oracle timing attack.

4

Which versions of phpseclib are affected by CVE-2026-32935?

CVE-2026-32935 affects phpseclib versions prior to 1.0.27, 2.0.52, and 3.0.50.

5

What is a padding oracle timing attack related to CVE-2026-32935?

A padding oracle timing attack exploits the timing discrepancies in error messages to decrypt encrypted data without knowing the key.

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