pkcs12: limit PBKDF iteration count to prevent CPU exhaustion by mohammadmseet-hue · Pull Request #343 · golang/crypto

mohammadmseet-hue · 2026-03-27T00:53:43Z

The PKCS#12 PBKDF iteration count is read directly from
the input file with no upper bound. A crafted 83-byte .p12
file can set iterations to 2^31-1 (2147483647), causing
Decode() to block a CPU core permanently.

This change adds a maximum iteration limit of 1000000 in
both verifyMac and pbDecrypterFor. Any file that specifies
more iterations than this cap is rejected with an error.

For reference, OpenSSL caps PBKDF2 at 10000000 iterations,
and scrypt is bounded by its memory-hardness parameters.
The 1000000 limit is generous for legitimate PKCS#12 files
while still preventing denial of service.

Fixes golang/go#78524

gopherbot · 2026-03-27T01:00:11Z

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gopherbot · 2026-03-27T01:09:05Z

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gopherbot · 2026-03-27T01:09:05Z

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The PKCS#12 PBKDF iteration count is read directly from the input file with no upper bound. A crafted .p12 file (83 bytes) with iterations set to MaxInt32 causes pkcs12.Decode() to block indefinitely. Add a maximum iteration count of 1 million. This is well above typical values (2048-10000) used by real PKCS#12 implementations while preventing malicious files from causing CPU exhaustion. The check is applied in both verifyMac (MAC verification) and pbDecrypterFor (content decryption), which are the two entry points that call pbkdf with the attacker-controlled iteration count. Change-Id: I38e327b3ef566631e6d5f27098efd3bc61b87d1e

gopherbot · 2026-04-03T15:18:33Z

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Patch Set 1:

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gopherbot · 2026-04-03T15:18:38Z

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gopherbot · 2026-04-03T18:18:38Z

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gopherbot · 2026-04-03T23:53:30Z

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gopherbot · 2026-04-06T19:49:14Z

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Patch Set 3:

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Tests verifyMac and pbDecrypterFor at the limit, over the limit, with negative values, and with max int. Updates golang/go#78524

gopherbot · 2026-04-06T20:10:44Z

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gopherbot · 2026-04-06T20:21:15Z

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gopherbot · 2026-04-06T20:21:16Z

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Patch Set 4: Code-Review+2 Commit-Queue+1

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gopherbot · 2026-04-06T20:21:16Z

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gopherbot · 2026-04-07T11:21:16Z

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gopherbot · 2026-04-07T17:34:12Z

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mohammadmseet-hue force-pushed the fix/pkcs12-iteration-limit branch from 008f0a8 to bc14ef1 Compare April 3, 2026 14:58

trigger GerritBot commit message rebuild

1e033b1

mohammadmseet-hue mentioned this pull request Apr 3, 2026

x/crypto/pkcs12: unbounded PBKDF iteration count allows CPU exhaustion golang/go#78524

Closed

pkcs12: add tests for iteration count boundary conditions

a0370d4

Tests verifyMac and pbDecrypterFor at the limit, over the limit, with negative values, and with max int. Updates golang/go#78524

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